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Universidad del Turabo
Efficiency of White-Rot Fungi on the Biodegradation of
Hydrocarbon
Contaminated Soil
By
Rita Ellen Koett Rosas,
B.S., Chemistry, University of Puerto Rico
M.M.C., Quality Management, Polytechnic University of PR
Dissertation
Submitted to the School of Science and Technology
in partial fulfillment of the requirements for
the degree of Doctor of Philosophy
in Environmental Science
(Management)
Gurabo, Puerto Rico
May, 2014
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Universidad del Turabo
A dissertation submitted in partial fulfillment of
the requirements for the degree of
Doctor of Philosophy
___April 03, 2014___
date of defense
Efficiency of White-Rot Fungi on the Biodegradation of
Hydrocarbon
Contaminated Soil
Rita Ellen Koett Rosas
Approved
Betsaida Torres García, PhD Carlos J. Olivo Delgado, EdD
Research Advisor Supervisor/Advisor
Angel L. Rivera, PhD Ramón Martínez Pacheco, PhD
Member Member
Teresa Lipsett Ruiz, PhD
Dean
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© Copyright 2014
Rita Ellen Koett Rosas. All Rights Reserved
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iii
Acknowledgements
The journey may become easier when you are with people who are
supportive. I have
experienced the same kind of atmosphere during the completion of
my dissertation work. It is a
pleasant aspect to have the privilege to evince a word of thanks
to everyone who made this
journey possible in a smooth manner.
I would like to express my deep, sincere and loving thanks to my
advisor Dr.
Betsaida Torres. Her valuable advice and guidance towards the
writing skills and overall
completion of this investigation have been very helpful for this
study. Her understanding and
personal guidance have provided a good basis for the present
investigation. Especially the strict
and extensive comments and many discussions and the interactions
with Dr. Torres had a direct
impact on the final form and quality of this dissertation.
I owe my sincere thanks to Dr. Carlos Olivo as the supervisor
advisor he has provided
valuable advice and guidance towards the writing skills and
overall completion of this
investigation. His extensive discussions around my work have
been very helpful for this study.
I owe my deepest thanks to Dr. Paul Bayman, Head of Department
of Biology from the
University of Puerto Rico, for his support during my
investigation while storing the fungus at his
laboratory and preparing the subcultures to maintain the fungus
during my investigation.
I warmly thank Maritza Vázquez and Altol Labs for her kind
support and guidance and
allowing to use the lab to perform the analytical testing
section. I wish to thank all the research
scholars and lab assistants for their help.
I have regard and wish to extend my warmest thanks to my
colleagues Jorge Hernandez,
Iris Cosme, Ivette Rivera, Adalberto Bosque for their
encouragement and understanding.
I feel a deep sense of gratitude for my family who formed part
of my vision and gave me
support along this path providing a sense of pride for the good
things that really matter in life.
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Above all, I’m grateful to almighty God for blessing me to
complete this work
successfully.
Rita Ellen Koett Rosas
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v
Vitae
Rita Ellen Koett Rosas, born in New York, USA, came to Puerto
Rico at an early age and
established on the east coast, Fajardo, with her parents. She
completed university studies at the
University of Puerto Rico, Río Piedras campus obtaining a
bachelor degree in Science in 1980
with major in chemistry. After almost twenty years working for
different pharmaceuticals and
medical devices industries she decided to pursue a master degree
in Manufacturing
Competitiveness with a major in quality management from
Polytechnic University of PR in 2005.
Actually in pursue of a doctoral degree in Environmental Science
from the Universidad del
Turabo. Since 1978 she has been working for different
pharmaceutical industries, medical
devices and consumer products companies thus occupying
managerial positions within in the
quality department of each company. As of August 2012, and
during the past four semesters,
have been offering courses in the areas of Good Manufacturing
Practices (GMPs), Validations
and Team Work to students registered to complete an Associate
Degree in Biotechnology at the
Universidad del Turabo, Gurabo campus.
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Table of Contents
Page
List of Tables
...........................................................................................................................
viii
List of Figures
..........................................................................................................................
ix
List of Appendix
......................................................................................................................
x
Abstract
....................................................................................................................................
xi
Resumen en español
.................................................................................................................
xii
Chapter One. Introduction
......................................................................................................
1
Section I. Bioremediation Executed
...........................................................................
1
Section II. Waste Disposal
..........................................................................................
3
Section III. Contaminants
...........................................................................................
4
Section IV. Soil Microorganisms
................................................................................
10
Section V. Lignin
........................................................................................................
13
Section VI. Fungi Bioremediation Techniques
........................................................... 17
Section VII. Intellectual Merit
....................................................................................
24
Chapter Two. Literature Review
.............................................................................................
27
Section I. Waste Production
........................................................................................
27
Section II. Bioremediation
..........................................................................................
29
Section III. Microorganisms in Bioremediation
......................................................... 32
Section IV. Soil in Bioremediation
.............................................................................
33
Section V. Fungi in Bioremediation
...........................................................................
37
Chapter Three. Methods
..........................................................................................................
44
Section I. Introduction
................................................................................................
44
Section II. Soil Profile
................................................................................................
45
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vii
Section III. Fungi
........................................................................................................
60
Section IV. Stock TPH Standard
................................................................................
62
Section V. TPH working standard solution
...............................................................
62
Section VI. Preparation of soil/water/TPH working standard
solution with five different
fungi
............................................................................................................................
62
Section VII. Soil/water/TPH working standard solution with most
effective degrading
fungi
............................................................................................................................
65
Section VIII. Selection of optimum conditions
.......................................................... 66
Section IX. Statistical analysis
....................................................................................
66
Chapter Four. Discussion
........................................................................................................
68
Section I. Introduction
................................................................................................
68
Section II. Results
.......................................................................................................
69
Chapter Five. Conclusion and Recommendations
..................................................................
93
Section I. Introduction
................................................................................................
93
Section II. Conclusion
.................................................................................................
93
Section III. Recommendations
....................................................................................
95
Literature Cited…
....................................................................................................................
97
Appendix One. Abbreviations
................................................................................................
118
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viii
List of Tables
Page
Table 1. LD50 values of some representative PAHs
............................................................ 8
Table 2. Environmental factors and optimum condition for
microbial activity
for soil bioremediation
.........................................................................................
35
Table 3. Sample size for TKN determination
.....................................................................
48
Table 4. Atomic absorption concentration ranges with direct
aspiration atomic absorption.
..............................................................................................................................
56
Table 5. Soil Profile, Coto clay, non-sterile
.......................................................................
70
Table 6. Soil Profile, Coto clay, sterile
..............................................................................
71
Table 7. TPH degradation rate for WRF Phanerochaete
chrysosporium
BKM-1767 isolate
................................................................................................
72
Table 8. TPH degradation rate for WRF Pleurotus djamor TU-7659
isolate .................... 74
Table 9. TPH degradation rate for WRF Pleurotus djamor native
strain
PR-1562 isolate
....................................................................................................
74
Table 10. TPH degradation rate for WRF Trametes elegans
FP-105038 isolate ................. 75
Table 11. TPH degradation rate for WRF Trametes elegans native
strain
PR-1151 isolate
....................................................................................................
76
Table 12. TPH degradation rate for most effective selected WRF
Trametes
elegans native strain PR-1151 isolate
..................................................................
77
Table 13. Factor and Model Summary for the five fungi tested
........................................... 81
Table 14. Analysis of Variance for the five fungi tested
...................................................... 81
Table 15. Factor and Model Summary for the three fungi tested
......................................... 86
Table 16. Analysis of Variance for the three fungi tested
.................................................... 86
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ix
List of Figures
page
Figure 1. Pleurotus djamor
...............................................................................................
21
Figure 2. Phanerochaete chrysosporium
..........................................................................
23
Figure 3. Trametes elegans
...............................................................................................
24
Figure 4. Summary of different bioremediation strategies for
typical hazardous wastes . 31
Figure 5. Timeframe of Trametes elegans native strain PR-1151
.................................... 78
Figure 6. Fungi relationship
.............................................................................................
80
Figure 7. Timeframe relationship
.....................................................................................
81
Figure 8. Fungi interaction of the same species
...............................................................
83
Figure 9. Time interaction of native isolates
....................................................................
83
Figure 10. Normal probability Plot for five fungi Two-Way ANOVA
test ....................... 84
Figure 11. Timeframe relationship
.....................................................................................
85
Figure 12. Fungi relationship
.............................................................................................
86
Figure 13. Time interaction of native isolate
......................................................................
88
Figure 14. Fungi interaction of native isolate
.....................................................................
88
Figure 15. Normal probability Plot for three fungi Two-Way ANOVA
test ..................... 89
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List of Appendix
Page
Appendix One. Abbreviations
..........................................................................................
118
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xi
Abstract
Rita Ellen Koett Rosas (PhD, Environmental Science)
Efficiency of White-Rot Fungi on the biodegradation of
hydrocarbon contaminated soil
(May/2014)
Abstract of a doctoral dissertation at Universidad del
Turabo.
Dissertation mentor: Betsaida Torres, PhD.
No. of pages in text 119
The pollution of soil and water by industrial effluents that
contain oil-waste is a problem
in our Island. This problem requires our full attention since
the waste treatment has a negative
impact on health, natural terrestrial ecosystem and natural
aquatic environment. Solutions that
might be used to solve this problem include, not limited to,
chemical treatments, degradation of
wastes, physico-chemical treatment to wastewater, and, in some
cases, even bioremediation.
The white-rot fungi (WRF), among which are Phanerochaete
chrysosporium, Pleurotus
djamor, and Trametes elegans, have been investigated by several
scientists due to their capability
for the degradation of hazardous wastes. They are able to
mineralize a wide variety of
chlorinated organics, polychlorinated biphenyls (PCBs),
polycyclic aromatic hydrocarbons
(PAHs), total petroleum hydrocarbons (TPHs), pesticides and
others.
In this investigation we will expose these WRF Phanerochaete
chrysosporium, Pleurotus
djamor, and Trametes elegans and their native species to a
contaminated soil and determine the
most effective WRF in soil remediation. Effects of different
inoculation times of the most
effective WRF found will be measured. Results will further
provide insights into the
development of contaminated soil biodegradation processes for
food safety and agriculture
sustainability.
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xii
Resumen
Rita Ellen Koett Rosas (PhD, Environmental Science)
Efficiency of White-Rot Fungi on the biodegradation of
hydrocarbon contaminated soil
(May/2014)
Resumen de disertación doctoral en Universidad del Turabo
Disertación fue supervisada por la Dra. Betsaida Torres
Total de paginas 119
La contaminación de suelos y aguas por efluentes industriales
que contienen aceite de los
residuos es un problema en nuestra isla. Este problema requiere
de toda nuestra atención ya que
el tratamiento de los residuos tiene un impacto negativo en la
salud, los ecosistemas terrestres
naturales y el medio ambiente acuático natural. Soluciones que
podrían ser utilizados para
resolver este problema incluyen, sin limitarse a, tratamientos
químicos, la degradación de los
desechos, tratamiento físico-químico de aguas residuales, y, en
algunos casos, incluso
biorremediación.
Los hongos de podredumbre blanca (WRF), entre los que se
Phanerochaete
chrysosporium, Pleurotus djamor y Trametes elegans, han sido
investigados por varios científicos
debido a su capacidad para la degradación de los desechos
peligrosos. Son capaces de
mineralizar una amplia variedad de compuestos orgánicos
clorados, bifenilos policlorados (BPC),
hidrocarburos aromáticos policíclicos (HAP), hidrocarburos
totales de petróleo (HTP), pesticidas
y otros.
En esta investigación vamos a exponer estos chrysosporium WRF
Phanerochaete,
Pleurotus djamor y Trametes elegans y sus especies nativas de un
suelo contaminado y
determinar el WRF más eficaz en la recuperación de suelos.
Efectos de diferentes tiempos de
inoculación del WRF más efectivo encontrado se medirán. Los
resultados serán proporcionar
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xiii
más conocimientos sobre el desarrollo de los procesos de
biodegradación de suelos contaminados
para la seguridad alimentaria y la agricultura
sostenibilidad.
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Chapter One
Introduction
Section I. Bioremediation Executed
Bioremediation is a technique used to remediate a contaminated
area, either soil or water
by means of use of biological processes. It can be used where
hazardous waste products are
degraded or detoxified by microorganisms or microbial processes
(Soetan 2011); it is very
popular and publicly accepted to remediate contaminated soil due
to its cost-effectiveness (Davis
et al. 1993) as it brings along environmental safety aspects.
This technique requires the presence
of a contaminant, an electron acceptor and the presence of
indigenous and/or augmented
microorganisms capable of degrading a specific contaminant.
Treating xenobiotic- contaminated
soils, for instance, requires the identification and
implementation of physico-chemical and/or
nutritional conditions to favor optimum growth, and
xenobiotic-degrading activities of indigenous
(biostimulation) or inoculated (bioaugmentation)
xenobiotic-degrading microbes (Lamar et al.
1999). Augmenting the contaminated site by using an appropriate
microorganism inoculum is a
technique that can enhance the biodegradation process of
hydrocarbons (Kristanti et al. 2011).
This approach allows for the selection of microbes based on
additional physiological,
biochemical, or ecological characteristics that may confer
bioremediation performance (Lamar et
al. 1999). Whereas, using indigenous microorganism consortium
ensures organisms with higher
tolerance to hydrocarbon toxicity to withstand variations on
environmental conditions (Kristanti
et al. 2011). It involves the selection of microbes based
primarily on their xenobiotic-degrading
activities (Lamar et al. 1999). There are many natural
populations (consortia) and
microorganisms that can perform different biodegradation
activities known for several decades
(Soetan 2011) including bacteria, yeast, fungi or algae.
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Whole microorganisms, either naturally occurring or introduced,
or isolated enzymes
which degrade persistent contaminants into none or less toxic
compounds in combination with
complementary physical, chemical or mechanical processes, can
improve the reliability and
effectiveness of detoxification (Alcalde et al. 2006). These
organisms can detoxify the
environment, consuming and breaking down pollutants until their
mineralization, a complete
transformation into CO2 and H2O (Jurado et al. 2011). Using
their own enzymatic pathways
(Ulfig et al. 2001), conversion into harmless byproducts such as
simpler organic compounds, or
immobilizing them into soil humic substances (Jurado et al.
2011) can help avoid problems of
contaminants in the soil.
Microbial biodegradation factors affecting success of the
process and enzymatic reaction
rate are nutrient availability, moisture content, pH, and
temperature of the soil matrix.
Bioremediation can use any kind of microorganism to clean-up
hazardous waste sites as it is the
safest, rapid, least disruptive, ecologically responsible
method, and the most cost-effective
treatment (Solomon et al. 1996; and Alcalde et al. 2006). In the
bioremediation process, a
contaminated site is exposed to microorganisms which produce
enzymes that can break down the
toxins, leaving behind harmless metabolic byproducts such as CO2
and chlorides (Solomon et al.
1996).
More than 1,000 different species of bacteria and fungi can be
used to clean-up various
forms of pollution. These microorganisms contain enzymes
involved in lignin-metabolism.
Laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase
(MnP) from white-rot fungi
(WRF) are among the most studied enzymes in bioremediation,
where Lac is involved in
detoxification of phenols, triclorophenols, and PAHs (polycyclic
aromatic hydrocarbons)
distributed in terrestrial and aquatic environments (Alcalde et
al. 2006). These enzymes,
peroxidases and laccase, are the key lignin degrading enzymes
with great potential in industrial
applications (Sumit and Vimala 2012). Upreti and Srivastava
(2003) propose two possible
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approaches to reduce the “vices” of such polymeric materials:
develop biodegradable commodity
plastic or identify potential microorganisms and a develop
protocol to effectively biodegrade the
polymeric materials. This investigation pursues the latter
approach.
Section II. Waste Disposal
Presently, there is increasing knowledge and awareness of the
health risks and
environmental impact associated with the waste handling process.
It is our responsibility to take
action in order to reduce this impact for the benefit of our
health and well being of future
generations.
Waste is classified in three basic groups: medical, infectious
and domestic waste.
Medical waste is accumulated by the result of patient’s
diagnosis, treatment or immunization of
human beings as stated by Altin et al. (2003); whereas the
infectious waste is waste that has been
in contact with a patient diagnosed with an infectious disease
and could eventually produce an
infectious disease as well (Altin et al. 2003). The United
States Environmental Protection
Agency (USEPA 1989B) defines domestic waste, as garbage or trash
consisting of everyday
items as product packaging, bottles, food scraps, and newspaper,
among others.
The USEPA (1989B) states “hospital waste”, also known as solid
waste, as any waste,
either biological or non-biological, that has been discarded and
not considered for further use. It
also includes, and not limited to, hazardous chemicals,
infectious, pathological, radioactive
wastes, stock cultures, blood and blood products, pharmaceutical
wastes, batteries, plastics,
disposable needles, syringes, scalpels, and sharp items (Altin
et al. 2003; and Oyeleke et al.
2008). The waste of interest in this investigation is the one
caused by petroleum spillage and/or
run-off oil caused during rainfall.
It was until the public awareness of blood borne diseases raised
in the early 1980s, when
the HIV (Human Immunodeficiency virus) and HBV (Hepatitis B
virus) caught our attention, that
serious concern arised on proper waste disposal directly in
landfills. For example, the amount of
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waste generated in US (United States) hospitals is approximately
6,670 tons per day, or about 1%
of the 158 million tons of MSW (Municipal Solid Waste) produced
annually (Rutala and Mayhall
1992). Today, it is required to pre-treat hospital waste
avoiding direct contact with any MSW in
the landfill. Treatments for these types of wastes include
autoclaves, retorts, microwave/chemical
disinfection systems, burial in covered pits, and encapsulation
by immobilizing compounds (Díaz
et al. 2005). Other treatments considered are point-of-use
needle destruction technology and
mechanical compaction/reduction system. However, all of this
“pre-treated” waste will still end
in the landfill, mixed with MSW, and producing an inadequate
final disposal of waste resulting in
negative impact on public health, the environment and the
ecosystems (Díaz et al. 2005).
Final waste disposal sites, known as landfills, are dumps where
the MSW is deposited
until it reaches a height that for esthetics or technical
reasons is considered to be the desirable
maximum and, upon closure, some soil is deposited on top
(Themelis and Ulloa 2007). This
accumulation of waste is a fundamental step in any current waste
management strategy causing
water and soil pollution, generating a large amount of leachates
into our ecosystems (Ellouze et
al. 2007) as does occur with run-off of fuel during rainfall
weather conditions.
Section III. Contaminants
Soil contamination is defined as the presence on or over any
land of any liquid or solid
waste of such quantity, nature or duration or under such
conditions that can affect or could affect
the human health or well being, animal or vegetation, or even
may interfere with the freedom of
life or the property (Oyeleke et al. 2008). Improper handling of
non-hazardous solid waste can
contaminate the soil with liquid leachate depending on the type
of waste, soil conditions and
water content; as a hazardous solid waste like fuel spillage due
to run-off during rainfall, if
improperly handled, can represent damage irreversible to the
soil for future agricultural use
(Oyeleke et al. 2008).
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Examples of main soil contaminants are insecticides, paints,
battery waste, hydraulic oil,
rupture of underground storage tanks, oil and fuel dumping or
spillage, and even pathogenic
waste, as part of the leachate. These pollutants can contaminate
the soil and water systems with
heavy metals that in turn produce ecological impacts on water
bodies and soil sites which lead to
an increased nutrient load, especially if they are essential
metals (Oyeleke et al. 2008). Pollutants
of these categories can broadly be classified as metal,
nonmetal, metalloid, inorganic, and organic
compounds (Brar et al. 2006). The organic contaminants comprise
aliphatic, alicyclic, aromatic,
and PAHs, halogenated and non-halogenated compounds, pesticides,
and explosives; while
inorganic pollutants can include metals such as Ag, Al, As, Be,
Cd, Cr, Cu, Hg, Fe, Ni, Pb, Sb,
Se, Zn, and radioactive elements and their derivatives (Brar et
al. 2006). Population increase and
industrial growth negatively impact on the production of
domestic, municipal and industrial
wastes, affecting its disposal to the landfill and water
bodies.
Leachates may contain heavy loads of organic chemicals and
ammonia nitrogen causing a
major source of contamination to surface water, fauna and flora
(Ellouze et al. 2007), overall
surrounding soil and ground water (Guo et al. 2009). The
leachate can produce excess of nutrients
and phosphates, consequently causing eutrophication, where a
body of water can develop a dense
growth of algae (Asamundo et al. 2005). As the dense growth of
algae and other organisms are
formed, their eventual decay depletes the shallow waters of
oxygen causing the death of aquatic
life and affecting the physico-chemical properties of the soil
and water systems such as pH, BOD
(Biochemical Oxygen Demand) and COD (Chemical Oxygen
Demand).
Overall, the principal concern associated with hydrocarbon waste
contaminants in soil
and water systems is the toxicity leading to health risk to
humans (Brar et al. 2006). For example,
vegetable consumption grown in soil with trace heavy metals will
be hazardous in the human
food chain producing an adverse effect on human and animal
health, causing defects or even
death (Soen 2011). As this pollution affects the microorganisms
living in these ecosystems, it
http://dictionary.reference.com/browse/algae
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creates an overall disparity in the Earth. Endocrine disruptors,
for instance, PAHs, PAEs
(phthalates), and polychlorinated biphenyls (PCBs), are detected
in landfill leachates (Lü et al.
2008). The degraded PCBs congeners with ortho, meta, and/or para
substitutions may contain up
to 209 possible combinations with a number of chlorine
substitutions in the biphenyl nucleus
varying from 1 to 10 (Federici et al. 2012), chemically and
physically stable, and resistant to
degradation in the natural environment (Borazjani et al. 2005).
The PCBs lipophilic properties
make them slightly soluble in water, readily soluble in oils,
causing bioaccumulation in the fatty
tissues of fish, birds, animals, and humans (Borazjani et al.
2005). Therefore, the exposure to
PCBs can be through ingestion of food or drinking water known to
be contaminated with this
product. Meanwhile, pollution as transportation, industrial
activities, incineration of refuse and
waste burning (Cerniglia 1997), gasification, and even, plastic
waste incineration, are some of the
sources of PAHs.
These chemicals and their derivatives are pollutants produced
via natural and
anthropogenic sources (Bishnoi et al. 2008), found in most
terrestrial ecosystems that arise from
industrial operations (Eibes et al. 2005), product of organic
materials occurring from natural
combustion as forest fires (Levin et al. 2003), and volcanic
eruptions (Romero et al. 2010). This
is a reason to confirm why USEPA has classified PAHs among
priority pollutants (Bishnoi et al.
2008; and Pozdnyakova 2012). The resultant products contain
hydrogen and carbon, well known
as hydrocarbons, which are a health concern for their toxic,
mutagenic, and carcinogenic
properties (Martens and Frankenberger, Jr. 1995; Bezalel et al.
1997; Daane et al. 2001; and
Levin et al. 2003).
Petroleum hydrocarbons (PHCs) are common site contaminants, not
generally regulated
as hazardous wastes. During environmental studies the family of
PHCs is known as TPHs. One
of the most common contaminants found in soil, known as
xenobiotic chemical constituents, are
categorized into four fractions of complex mixtures as saturates
(aliphatics), aromatics, resins and
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7
asphaltenes (Ogbo and Okhuoya 2008) plus constituents that may
contain N, S or O in addition to
H and C (Robertson et al. 2007). These chemicals are purposely
released into the environment
via the dumping of petroleum waste or wastewater or as a result
of accidents during the
production, transport and use of chemicals (Jayasinghe et al.
2008). TPHs are complex mixtures
of hundreds of hydrocarbon compounds, ranging from light,
volatile, short-branched organic
compounds (aliphatic), which comprise the light fraction of
refined oil, to heavy, long-chained,
branched compounds. The aliphatic compounds primary source of
entry into the environment is
via emissions from combustion processes, spillage of petroleum
products (Rockne and Reddy
2003) by surface spills or leaks from pipelines, flow lines,
delivery line failures (Olusola and
Ejiro 2011), storage tanks (Robertson et al. 2007) and run-off
waters. The chemical composition
of the product can be affected by weathering and/or biological
modification upon release to the
environment. Therefore, the contamination changes the
physico-chemical and biological
properties of the soil being toxic to some soil microorganisms,
plants (Ogbo and Okhuoya 2008),
animals and, even, people (Mohsenzadeh et al. 2012).
Hydrocarbons have been found to bio-
accumulate in aquatic organisms constituting a significant
health risk for people living in
industrialized areas of the world (Cerniglia 1992). To obtain an
effective TPHs aerobic
biodegradation the soil needs to have sufficient oxygen and
enough soil water to provide a habitat
for adequate populations of active microorganisms. If oxygen is
present, these organisms will
generally consume available TPHs. Furthermore, aerobic
biodegradation of petroleum
compounds can occur relatively quickly, with degradation
half-lives as short as hours or days
under some conditions (DeVaull, 2007).
Table 1. LD50 values of some representative PAHs (adapted from
Bamforth and Singleton 2005).
Material Number of
carbon rings
LD50 value
(mgkg-1
)
Test subject Exposure route
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8
Naphthalene 2 533-710 Male/female
mice respectively
Oral
Phenanthrene 3 750 Mice Oral
Anthracene 3 >430 Mice Intraperitoneal
Fluoranthene 4 100 Mice Intravenous
Pyrene 4 514 Mice Intraperitoneal
Benzo[a]pyrene 5 232 Mice Intraperitoneal
Generally, toxicity increases with an increase in number of
benzene rings, but data should be examined using careful
consideration of the exposure route, etc (data taken from the
Risk Assessment Information System (RAIS)
http://risk.lsd.oml.gov).
Table 1 depicts chemical compounds that are composed of fused,
aromatic rings whose
biochemical persistence arises from dense clouds of π-electrons
on both sides of the ring
structures, making them resistant to nucleophilic attack
(Johnsen et al. 2005). Materials with a 5-
ring hydrocarbon structure known as BaP (Benzo[a]pyrene), a
petroleum, coal tar and fuel-oil
component, are very recalcitrant and resistant to microbial
degradation formed upon the pyrolisis
of organics (Romero et al. 2010). Even though PAHs are
persistent, due to their high
hydrophobicity, low water solubility (Bishnoi et al. 2008; and
Okparanma et al. 2011), and high
solid-water distribution ratios, they are easily adsorbed onto
organic matter as soils and sediments
(Eibes et al. 2005), standing against their ready microbial
utilization, and promotion of their
accumulation in the solid phases of the terrestrial environment
(Johnsen et al. 2005), a great
variety of microorganisms (bacteria and fungi) can degrade
them.
There also exist xenobiotics compounds in waste that are
man-made synthetic organic
chemicals very difficult to degrade, foreign to the biosphere,
as they accumulate in the
environment and cause harmful, deleterious effects on the living
system (Sharma 2010).
Xenobiotic compounds are recalcitrant toxic pesticides,
hydrocarbon pollutants of the soil; the
main sources of contamination are the spills and leaks of
petroleum products (George-Okafor et
http://risk.lsd.oml.gov/
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9
al. 2009). These halogenated aliphatic and aromatic compounds
like DDT (1,1,1-trichloro-2,2-
bis(4-chlorophenyl) ethane), BHC (benzene hexachloride), PCBs,
polyethylene, polystyrene and
PVC (polyvinyl chloride) are not easily biodegradable due to the
extensive branching of the
molecule or introduction of halogen, nitro or sulphonyl group
(Sharma 2010). The same occurs
with the gamma isomer of hexachlorocyclohexane (γ-HCH), commonly
known as lindane, an
organochlorine compound widely used in the past in the
agricultural sector for its insecticidal
properties; however, its stability and hydrophobicity make them
persistent pollutants and their
toxicity also creates environmental and human exposure concerns
(Rigas et al. 2008). Another
xenobiotic compound is known as atrazine,
2-chloro-4-(ethylamino)-6-(isopropylamino)-s-
triazine (ATZ), a non-selective herbicide for vegetation control
in non-crop land, and one of the
most widely used herbicides in the world for the control of
annual grasses. It has led to the
contamination of terrestrial ecosystems, and can be measured in
ground and surface water in
many countries, constituting a public health and environmental
concern of pesticide
contamination (Mougin et al. 1994). Finally, fenthion’s
degradation products, particularly the
sulphone and sulphoxide derivatives, can be persistent depending
on environmental conditions
when applied to an affected area. This organophosphorous
pesticide was used to control bird
pests in agricultural systems, (Zacchi et al. 2000).
Waste leachate may also contain BTEX compounds (benzene,
toluene, ethylbenzene, and
o-, m- and p-xylenes), an important family of organic
pollutants, components of gasoline and
aviation fuels. They and their nitro derivatives are widely used
in industrial syntheses, considered
carcinogenic and neurotoxic, and classified as priority
pollutants (Levin et al. 2003). Another
contaminant released into the environment, 2,4,6-Trinitritoluene
(TNT), predominates in soil and
groundwater at many sites of TNT production. It is a
recalcitrant, mutagenic compound shown to
be toxic to gram-positive bacteria, yeasts, and fungi as well as
green algae (Michels and
Gottschalk 1994).
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10
It is essential to contain or mitigate these organic and
inorganic contaminants so as to
prevent them from contaminating surface and groundwater by
dissolution or dispersion (Brar et
al. 2006). Control methods which are less damaging to the
environment are urgently sought, with
remediation of contaminated sites being a priority (Zacchi et
al. 2000).
Section IV. Soil Microorganisms
USEPA has indicated that soil pollution is a threat to the
environment, to food safety and
to a sustainable agriculture as there is a direct link between
the health of the ecological
environment and the health of humanity (Bonaventura and Johnson
1997). Nevertheless,
pollution prevention and environmental remediation are
interwoven into strategies proposed for
sustaining human and environmental health; it involves enhanced
degradation of toxic
compounds by transforming them into innocuous substances (Brar
et al. 2006), the primary
stimulant in bioremediation of contaminated environments
(Bonaventura and Johnson 1997).
The variety of contaminants, their synergistic and antagonistic
effects, and their physico-
chemical properties make them serious toxicants, which may
survive different treatments. Soils
possess great diversity of microorganisms in terms of their
inherent physical, chemical and
biological characteristics (Jones et al. 2009). These ecosystems
retain a set of intrinsic biological
functions independent from location as the major input of
organic matter is plant residues,
composed mainly of the same primary building blocks (cellulose,
hemicellulose, protein, lignin
and lipids), leading to the formation of a soil organic matter
of similar chemical structure (Jones
et al. 2009).
In the majority of the cases, soils are classified according to
the primary factors that
regulate their formation (time, climate, parent material,
topography and vegetation), thus
implying they behave differently from one another (Jones et al.
2009). Even though they possess
different sets of organisms, all soil microbial communities
might be expected to retain a core set
of functions such as protein and cellulose degradation. The
microorganisms require carbon, an
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11
energy source, to sustain the metabolic functions, growth and
reproduction (Sen and Chakrabarti
2009), and to digest the contaminated material as nutrient,
hazard to humans, converting them
into non-hazardous products as CO2 and water. Biological
decomposition techniques include the
use of natural microorganisms such as bacteria, yeast, fungi and
algae to degrade the toxic
material into a less toxic one. The successful use of microbial
inocula in soils requires the
microorganism to have contact with the contaminant as physical
adsorption to soil particles or
filtration through the soil small pores limits the transport of
organisms (Márquez-Rocha et al.
2001).
For instance, both aerobic and anaerobic bacteria have been
shown to degrade BTEX
compounds, but most of these studies on bacterial degradation of
BTEX have used microbial
consortia and no native strain of bacterium is known to degrade
all the components efficiently as
o-xylene, particularly, has been shown to be recalcitrant to
bacterial degradation (Levin et al.
2003). Therefore, the biological treatment using WRF and their
enzymes, prove to be a success
in the elimination of non-stabilized organic matter and toxic
compounds in the range of
xenobiotic environmental pollutants (Ellouze et al. 2007). Many
xenobiotics chemical
constituents (TPHs) are structurally analogous to compounds
naturally found in the soil
environment (plant material, fungal and root exudates and
allelophatic chemicals) and appear to
be biodegraded through the same biochemical pathways (Robertson
et al. 2007). There is
evidence that bioremediation of hydrocarbon contaminated soil by
the use of microorganisms is
an efficient, inexpensive, adaptable, and an environmentally
sound treatment method
(Adenipekun et al. 2011). These treatments are a major source of
renewable organic matter such
as lignocelluloses since its chemical properties allows it to be
a substrate of great
biotechnological value, consisting of lignin, hemicellulose and
cellulose, found in woody plants
(Jafari et al. 2007), dead plant materials, and is the most
abundant biomass on Earth (Kalmiş et al.
2008).
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12
Indigenous microorganisms are used as a bioremediation strategy
at polluted sites to
degrade PAHs by improving their in-situ degradation capability
through the optimization of
temperature, pH, water-content, and oxygen concentration
(Bishnoi et al. 2008). Whereas
introduced species, as the ones used for this investigation, may
be presumed to be involved in
PAHs degradation techniques as possible bioremediation processes
(Bishnoi et al. 2008). The
degradation of PAHs is favored at nitrogen-limiting conditions
and low pH (about 4.5) making
bioremediation technique an efficient, economic, versatile, and
environmentally sound treatment
(Bishnoi et al. 2008). Biodegradation of PAHs with WRF occurs
similar to the lignin polymer
degradation process of the carbon cycle of the biosphere.
Section V. Lignin
Lignin has its origin in the Latin word “lignum” which means
wood (Wong 2009). This
compound is a three-dimensional biopolymer with a high molecular
weight considered the most
abundant renewable source of aromatic polymer on the earth,
important constituent of the living
terrestrial biomass and, therefore, a resistant material to
microbial degradation (Magan et al.
2010). It can be synthesized in plants by linking
hydroxycinnamyl, coniferyl and sinapyl alcohols
to obtain p-hydroxyphenol (Tišma et al. 2010). Lignin (the main
component of wood) cellulose
and hemicellulose are the main constituents of the chemical
substance called lignocellulose
(Tišma et al. 2010). Bioconversion of lignin is one of the most
important processes occurring in
the carbon cycle of the biosphere (Rogalski et al. 1991). This
polymer is highly oxidized,
therefore, difficult to oxidize further as a complex
hetero-polymer with no stereo-chemical
regularity due to its free radical mechanism of synthesis. WRF
are the most efficient lignin
degraders in nature, due to their ability to degrade complex and
recalcitrant organic molecules.
This property makes them attractive microorganisms for
bioremediation of soil contaminated by
organic pollutants. Xenobiotics chemicals, for instance, can
only be degraded by the unspecific
extracellular ligninolytic enzymes WRF can produce.
-
13
These microorganisms can eventually degrade lignin when the
mycelia of the organisms
penetrate the cell cavity and release ligninolytic enzymes to be
able to decompose xylon, a small
fungi grown on trees, to a white sponge-like mass (Gao et al.
2010). They are the only ones
known to be able to degrade the highly recalcitrant natural
polymer lignin or lignin model
compounds, by producing three types of extracellular enzymes
known as lignin-modifying
enzymes (LMEs); LiP, MnP and Lac (Gao et al. 2010).
Subsequently, the lignin biodegradation
must involve a non-specific and non-stereo-selective mechanism
in soil like the biodegradative
mechanisms found in these WRF (Aust 1995).
The mechanism of the lignin depolymerization applicable to
peroxidases is one in which
numbers of cationic radicals are generated during oxidation of
the lignin complex functioning as
lignin-degrading peroxidases (LDPs) substrates (Singh and Chen
2008). The ferric form of the
enzyme, referred as resting enzyme, is oxidized by two-electrons
using hydrogen peroxide (H2O2)
to a form of peroxidases known as compound I (Aust 1995). This
compound can be reduced by
one-electron by means of chemicals having a suitable reduction
potential (Aust 1995). Then, the
enzyme is reduced to a form called compound II whereas the
chemical is oxidized by one-
electron (Aust 1995). This one-electron oxidized chemical, or
the original chemical, can
eventually reduce compound II back to resting enzyme (Aust
1995). In order to be oxidized by
two-electrons (compound I), one-electron is removed from ferric
iron to form ferryl while the
second electron is withdrawn from the porphyrin ring. The latter
is reduced first to form
compound II so the reduction potential for compound I is
slightly higher than for compound II
(Aust 1995).
The WRF Trametes (Coriolus, Polyporus) versicolor, Phanerochaete
chrysosporium and
Phlebia radiata are among the most efficient lignin-degrading
microorganisms (Rogalski et al.
1991). T. versicolor produces all the enzymes and the same refer
to P. radiata, while P.
chrysosporium has been by far the most popular fungus in lignin
biodegradation research, it
-
14
produces only LiP and MnP, not Lac. Typical for the occurrence
of lignin-modifying enzymes in
T. versicolor seems to be the large variability between strains
which may reflect inherent
heterogeneity of this species. The production of Lac of T.
versicolor is stimulated by starvation
or by some phenolic compounds added to the growth medium.
Culture conditions are also
important for the production of lignin-modifying enzymes by
other fungi. The ligninolytic
activity of P. chrysosporium can only be seen after the primary
growth phase when carbon,
nitrogen or sulphur limitation occurs. Aromatic substances such
as veratryl alcohol are added to
the medium as stimulators, as the secondary metabolite, involved
in lignin degrading systems,
which increases the production of LiP in P. chrysosporium and in
P. radiata.
LiP acts in the oxidation of non-phenolic phenylpropanoid units
which lead to the
deconstruction of lignin polymer oxidizing aromatic nuclei to
aryl cation radicals which
eventually undergo several non-enzymatic reactions, including
cleavage of C-C and C-O linkages
(Singh and Chen 2008). This enzyme oxidizes non-phenolic lignin
substructure of aromatic
nuclei attracting one-electron in the presence of H2O2
generating cation radicals whose
spontaneous reactions lead to extensive degradation of lignin
(Periasamy and Natarajan 2004)
while in the oxidation of non-phenolic phenylpropanoid units it
can lead to polymer
fragmentation (Kalmiş et al. 2008).
Whereas, MnP, one of the important enzymes of fungi, oxidizes
Mn2+
to Mn3+
in the
presence of H2O2, allowing the attack of phenolic structures in
lignin with low redox potential
stabilized by suitable metal chelators secreted by the fungi
(Kalmiş et al. 2008). Initially, Mn2+
is
oxidized by both MnP I and MnP II compounds, generating Mn3+
. Then, Mn3+
is stabilized by
chelation with organic acids such as oxalate and malonate
produced by the fungal cells, and
diffuses from the surface of the enzyme as Mn3+
complex which in the end oxidizes the organic
substrates (Singh and Chen 2008).
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15
Finally, Lac enzymes have the capacity to oxidize phenolic and
non-phenolic compounds
and the ability to decolorize dyes in wastewaters (Ellouze et
al. 2007). These are the most widely
present enzymes in the nature, the oldest and most studied
enzymatic systems, as it contains 15-
30% carbohydrate and have a molecule mass of 60-90 kDa (Shraddha
et al. 2011). Glycosylated
polyphenol oxidases contain 4 copper ions per molecule, carry
out 1 electron oxidation of
phenolic and its related compound, and reduce oxygen to water,
so the copper containing, 1,4-
benzenediol: oxygen oxidoreductases (EC 1.10.3.2) can be found
in higher plants and
microorganisms.
When a substrate is oxidized by a laccase, it loses a single
electron and forms a free
radical that may undergo oxidation or non-enzymatic reactions
including hydration,
disproportionation, and polymerization. This enzyme plays an
important role in soil
bioremediation, biodegradation of environmental phenolic
pollutant, and removal of endocrine
disruptors. It is also used in nanotechnology, due to its
ability to catalyze electron transfer
reactions without additional co-factor (Shraddha et al. 2011).
Catalysis can occur when reduction
of one oxygen molecule to water is accompanied with the
oxidation of one-electron in a wide
range of aromatic compounds including polyphenols, and aromatic
amines. Lac enzymes are
secreted out in the medium extracellularly, and temperature and
pH are limiting factors for these
enzymes, as they differ from one strain to another. The optimal
temperature of Lac enzymatic
production is found to be 25ºC in presence of light, while, in
the dark the optimal temperature is
30ºC, and the pH will occur within 4.5 and 6.0 (Shraddha et al.
2011). Lac is widely distributed
in higher plants, bacteria, fungi, and insects and has been
isolated from Ascomyceteous,
Deuteromycteous and Basidiomycetous fungi. The white-rot
Basidiomycetes fungi efficiently
degrade the lignin which oxidizes phenolic compounds to give
phenoxy radicals and quinines.
Microorganisms inoculated into the solid-phase remediation of
soil (Davis et al. 1993)
can release enzymes, which play an active key role in the
biological, and biochemical
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16
transformation of the matrix. The enzymes are responsible for
the breakdown of several organic
compounds characterized by a complex structure finally producing
simple water-soluble
compounds (Zeng et al. 2010). There may be pollutants bound to
soil particles less available to
enzymatic processes being much more resistant to degradation
(Davis et al. 1993).
Conclusively, there can be a biotechnology application to
improve the contaminated soil
by means of whole microorganisms or their enzymes to synthesize
or bioconvert the
contaminated material into new product (Jafari et al. 2007). The
use of WRF for soil
bioremediation can potentially contribute to a safer environment
by decreasing or completely
eliminating harmful contaminants, while improving soil
conditions for cultivation purposes.
This investigation aims to provide evidence of degradation
effectiveness for selected
WRF; Phanerochaete chrysosporium BKM-1767, Pleurotus djamor
TU-7659, Trametes elegans
FP-105038, Pleurotus djamor native strain PR-1562 and Trametes
elegans native strain PR-1151
and will not investigate enzymatic actions.
Section VI. Fungi Bioremediation Techniques
Fungi are an important contributor to the ecological balance of
the world (Solomon et al.
1996). Like bacteria, most fungi are saprotrophs (also called
saprobes), decomposers that absorb
nutrients from organic waste and dead organisms. Once fungi
degrade wastes and dead
organisms, water, carbon (as CO2) and mineral components of
organic compounds are released,
and these elements are recycled (Solomon et al. 1996). If this
continuous decomposition does not
occur, essential nutrients can be locked-up in huge mounds of
dead animals, feces, branches, logs,
and even leaves. Then, the nutrients are not available for use
by new generations or organisms;
therefore, life can cease (Solomon et al. 1996). In Puerto Rico
there are forests which contain
fungi playing an important role in ecosystems to help decompose
organic matter by releasing
nutrients that may become available to plants (Lodge et al.
2007). For this reason WRF native
strains will be used for biodegradation purposes of a
hydrocarbon contaminated soil.
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17
Fungi contain genetic information that can make them very
efficient in the adaptability to
extreme environmental conditions of water, temperature, pH and
salinity as indicated by Lacina
et al. (2003) and Cantrell et al. (2006). The enzymes released
by the fungi will help in the
remediation process of the soil portion affected by the
polluted-waste leachate compounds as
mentioned in studies by Davis et al. (1993) when using
lignin-degrading fungi to degrade
chemicals as creosote and/or PCP (pentachlorophenol). Other
compounds that can be oxidized by
white rot fungi are chlorinated phenols, PCBs, dioxins,
pesticides, explosives, TPHs and, even,
dyes (Levin et al. 2003). These fungi cause the “white-rot” of
wood, as well as litter
decomposition, by breaking down lignin which require
extracellular enzymes and are better
candidates for the bioremediation of highly apolar pollutants
than non-ligninolytic
microorganisms (Levin et al. 2003).
The WRF are unable to supply all their carbon and energy
requirements from lignin.
Therefore there is a need of substrates as cellulose or other
carbon sources for their growth and
delignification to make them a highly potential material for
degradation of various xenobiotic
compounds and dyes (Kalmiş et al. 2008), as to ease degradation
of high molecular-mass organic
pollutants (extracellular fungal enzymes) (Ellouze et al. 2007).
In this investigation we
incorporated hay into the soil mixture as a source of carbon
content to support the growth, and to
facilitate the degradation process by WRF. If we were to compare
the degradation ratio of WRF
versus the bacteria, there are not all microbial bacteria known
that can degrade all components of
BTEX compounds (Levin et al. 2003) while Phanerochaete
chrysosporium simultaneously has
degraded all the BTEX components (Levin et al. 2003). This WRF
was the focus of our
investigation as there are studies indicating the degrading
effectiveness on contaminated sites.
Other WRF as Pleurotus tuber-regium (Ejoh et al. 2012),
Polyporus sp. S133 (Hadibarata and
Tachibana 2009), and Lentinus subnudus (Adenipekun and Fasidi
2005) have been evaluated with
notable differences regarding to the extent of their pollutant
transformation ability. The
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18
intracellular process used by bacteria does not have access to
degrade pollutants as does the
extracellular enzymes produced by WRF.
The observation that white-rot fungi can oxidize PAHs rapidly
with their extracellular
ligninolytic enzyme systems has therefore raised interest in the
use of these organisms for
bioremediation of PAH-polluted soils as mentioned by Levin et al
(2003). The non-specific
oxidases involved in lignin degradation (mainly laccases,
lignin- and manganese-peroxidases) are
able to transform by oxidation the PAHs to a more water-soluble
product with much greater
bioavailability (Levin et al. 2003). The use of white-rot fungi
for bioremediation requires an
understanding of the factors that enhance their ability to
detoxify, and clarification of the enzyme
mechanisms used (Levin et al. 2003).
During a bioremediation process the enzymatic degradation is
selected as an alternative
to bacterial processes as the biological degradation requires
long periods of treatment (from 2 to 4
weeks) and presents lag phases (2 days) until degradation can be
observed (Eibes et al. 2005).
The optimal growth of WRF occurs at 102ºF, pH range of 4.0 to
4.5, and high oxygen content.
Lignin degradation using pure oxygen is 2 to 3 times greater
than with air. The growth rate of
WRF increases significantly when the water potential increases
from 1.5 to 0.03 MPa
(MegaPascal=106 Pa), and growth in soil increases directly with
nitrogen content and optimal
moisture content of 40-45% (Eibes et al. 2005).
The first steps in the biotransformation of PAHs were
investigated by Bezalel et al (1997)
using two phase I enzymes, cytochrome P-450 monooxygenase and
epoxide hydrolase.
Intracellular systems generally present in most fungi, such as
cytochrome P-450 monooxygenase,
can also be involved in organopollutant degradation (Levin et
al. 2003). There is a potential for
phase II biotransformations (formation of sulfates,
glucuronides, glucosides, or glutathione
conjugates from phenolic derivatives of the PAHs), since there
is water-soluble metabolite, which
could be conjugation products (Bezalel et al. 1997). While for
xenobiotics compounds such as
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19
2,4-dinitrotoluene and 2,4,5-trichlorophenol, the multi-step
catabolic pathways were shown to
involve cycles of intracellular reductions and extracellular
oxidations, terminating in intracellular
oxidative ring cleavage prior to complete mineralization (Zacchi
et al. 2000).
The WRF belonging to the basidomycetes as Pleurotus species
(Periasamy and Natarajan
2004) (Figure 1) produce various extracellular LMEs with very
low substrate specificity as LiP,
MnP, H2O2 producer enzymes, aryl alcohol oxidase and Lac. These
species produce protein rich
biomass of fruiting bodies, enabling to mineralize a wide range
of highly recalcitrant organo-
pollutants structurally similar to lignin (Kalmiş et al. 2008)
and a wide range of xenobiotic
compounds (Faraco et al. 2009). Pleurotus species possess the
capacity to accelerate the
biodegradation of organic pollutants (Ellouze et al. 2007) and
reduce more than 95% of PAHs
inoculated into test soil to non-toxic components (Adenipekun
and Isikhuemhen 2008).
Figure 1. Pleurotus djamor (The Hidden Forest, 2005).
The biosynthetic potentialities of these species are the
production and secretion of a wide
spectrum of enzymes enabling to thrive over a wide range of
plant wastes, since changes of
extracellular enzyme activities of cellulases and laccases are
directly correlated with growth and
fruit body formation (Periasamy and Natarajan 2004). To
establish a different relationship
-
20
between LiP and MnP, the first is characterized by oxidation of
high redox-potential aromatic
compounds as veratryl alcohol while MnP requires Mn2+
to complete the catalytic cycle forming
Mn3+
chelates which act as diffusing oxidasers (Periasamy and
Natarajan 2004), thereby
generating aromatic radicals (Sánchez 2010). The LiP activity
may be defined as the enzyme
amount leading to produce 1 μmol veratryl aldehyde by the
oxidation of veratryl alcohol per
minute. Whereas MnP activity is expressed as the enzyme amount
to produce 1 μmol of Mn3+
by
the oxidation of Mn
2+ per minute.
For Lac the activity is expressed as the enzyme amount which
leads to the oxidation of 1
μmol of 2,2-azino-bis-[3[ethyltiazoline-6-sulfonate] (ABTS) per
minute (Zeng et al. 2010). The
specific activities of the enzymes may be expressed as units per
gram of dry medium. These
WRF species also are able to breakdown all components of
lignocellulose, fraction of the total
organic matter, from composted agricultural waste, including
lignin, being more refractory to
microbial attack, once lignocellulolytic microorganisms are
inoculated in the soil as a strategy to
enhance lignocellulose degradation (Zeng et al. 2010). As the
fungi have the ability to degrade
several lignocellulose substrates it can be produced on natural
materials from agriculture,
woodland, animal husbandry, and manufacturing industries
(Sánchez 2010).
Another well-known WRF is Phanerochaete chrysosporium (Figure
2), the most active
ligninolytic organism for its ability to degrade/mineralize
lignin including soil humic substances
(Winquist et al. 2009). Additionally, it degrades a wide variety
of aromatic compounds as
chlorinated organics, PCBs, PAHs, pesticides and others (Aust et
al. 1994), by its non-specific
oxidative and extracellular multi-enzyme system (Ballaminut and
Matheus 2007), involving MnP,
LiP and Lac (Zeng et al. 2010) and other enzymes. This fungi is
capable of degrading starch,
cellulose, pectin, lignin, lignocelluloses, and can decolorize
azo-triphenyl methane dyes
(Asamundo et al. 2005) and complex organic substances as
halogenated aromatics (dioxin), and
many others (Singh and Chen 2008). This WRF also degrades a wide
range of PAHs including
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21
acenaphthene, acenaphthylene, anthracene,
benzo(a)anthracene,
enzo(a)pyrene,benzo(b)fluoranthene, benzo(g,h,i)perylene,
benzo(k)fluoranthene, chrysene,
fluorene, indeno(1,2,3-c,d)pyrene, naphthalene, phenanthrene,
and pyrene (Kristanti et al. 2011).
Figure 2. Phanerochaete chrysosporium
(microbewiki.kenyon.edu227)
P. chrysosporium is the model of WRF for the production of
peroxidases attracting a
growing interest for the bio-treatment (removal or destruction)
of wastewater ingredients such as
metals, inorganic nutrients and organic compounds (Lacina et al.
2003). Physiological level of
oxalate in Phanerochaete chrysosporium cultures stimulates the
MnP activity (Singh and Chen
2008). This species is capable of degrading PCBs by transforming
a variety of cogeners with
varying degrees and position of chlorine substitutions
(Borazjani et al. 2005).
Finally, the genus Trametes (Figure 3) is probably the most
actively investigated in the
phylum of Basidiomycota for lignolytic enzyme formation and
application (Nyanhongo et al.
2007). The use of this WRF for remediation purposes is the
constitutive, extracellular secretion
and the non-specific nature of the lignolytic enzymes, which
obviates the need for adaptation to
the target molecule (Nyanhongo et al. 2007).
https://www.google.com.pr/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=bYwpo1q8nvKBYM&tbnid=38oyQ1EMtswLSM:&ved=0CAQQjB0&url=https%3A%2F%2Fmicrobewiki.kenyon.edu%2Findex.php%2FPhanerochaete_chrysosporium&ei=ZW9NU5rDFqehsQTiloHwCg&bvm=bv.64764171,d.dmQ&psig=AFQjCNEg5ZrICRR8khn1O5AZMxV12CjeAA&ust=1397669974976657https://www.google.com.pr/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&uact=8&docid=bYwpo1q8nvKBYM&tbnid=38oyQ1EMtswLSM:&ved=0CAQQjB0&url=https%3A%2F%2Fmicrobewiki.kenyon.edu%2Findex.php%2FPhanerochaete_chrysosporium&ei=ZW9NU5rDFqehsQTiloHwCg&bvm=bv.64764171,d.dmQ&psig=AFQjCNEg5ZrICRR8khn1O5AZMxV12CjeAA&ust=1397669974976657
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22
These species grow in inexpensive media such as straw or sawdust
and their hyphal
growth form allows them to extend far from their original
starting point, very attractive for soil
bioremediation purposes. The lignolytic enzymes available in
this species are Lac and MnP as
LiP is rarely reported and additional oxidoreductases as
cellobiose dehydrogenase (CDH) and
pyranose 2-oxidase (P2O) are also found in this species.
Figure 3. Trametes elegans (www.wisconsinmushrooms.com)
Section VII. Intellectual Merit
Soil contamination is a threat to the health of ecological
systems (alter plant metabolism
by reducing crop yields), the environment and human population.
The main objective of this
research was to determine the efficiency of a WRF from
Phanerochaete chrysosporium,
Pleurotus djamor, and Trametes elegans spp. as a viable strategy
for bioremediation of
contaminated soil and as a means to restore it to a healthful
state conducive to its use for safe
agricultural purposes. This research pursued the use of WRF’s
natural biological ability to
http://www.wisconsinmushrooms.com/
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23
destroy contaminant pollutants. The ultimate goal was to
investigate a remediation process that
could contribute both to food safety and sustainable
agriculture.
As the WRF can be used for soil bioremediation, the hypothesis
of this study was to
demonstrate the degrading effectiveness on the hydrocarbon waste
pollutant in a soil.
a) Null hypothesis (Ho): μ1- μ2- μ3- μ4 = 0; WRF- Phanerochaete
chrysosporium,
Pleurotus djamor, and Trametes elegans or native fungi have the
same degrading
effectiveness on hydrocarbon waste pollutant in soil.
b) Alternative hypothesis (Ha): μ1- μ2- μ3- μ4 ≠ 0; WRF-
Phanerochaete
chrysosporium, Pleurotus djamor, and Trametes elegans or native
fungi do not
have the same degrading effectiveness on hydrocarbon waste
pollutant in soil.
As part of the investigation, we would like to provide
significant evidence for a
bioremediation technique that can potentially enable a
contaminated site to be re-conditioned as a
contaminant free-soil for use in agriculture and farming. Soil
pollution is a threat to the
environment, to food safety and to a sustainable agriculture.
WRF, Phanerochaete
chrysosporium, Pleurotus djamor, and Trametes elegans, were
introduced to a contaminated soil
affected by hydrocarbon waste pollutant. These microorganisms
are capable to degrade the
contaminant measuring the effects at different inoculation
intervals.
This investigation is a ground breaking study using native WRF
from Puerto Rico as a
soil restoration technology, in order to develop innovative,
biologically safe and cost-effective
treatments for removing hydrocarbon waste pollutants from soil
that cannot be performed by
existing chemical processes; accomplished by using rainfall and
adding TPH contaminant to a
known soil.
Topics to be explored during the completion of this
investigation are:
1) What are the ideal conditions for effective degradation
process of WRF-
Phanerochaete chrysosporium, Pleurotus djamor, and Trametes
elegans or their
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24
native fungi to reduce or eliminate the hydrocarbon pollutant
contamination in
soil produced by uncontrolled waste management?
2) Which WRF species is the best candidate for a scale-up
bioremediation study
based on the degrading effectiveness in a soil used for
agricultural purposes?
3) What is the degradation rate at which the most effective WRF
degrades a
petroleum related contaminant in soil?
4) Can a bioremediation strategy to mitigate soil hydrocarbon
contamination caused
by petroleum related waste leachate be implemented?
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25
Chapter Two
Literature Review
Section I. Waste Production
Bio-medical waste is any solid and fluid including its container
and any intermediate
product, generated during the diagnosis, treatment or
immunization of human beings or animals,
in research activity (Sarojini et al. 2007), biological
production or testing. There are two
categories for bio-waste known as non-hazardous (85%), where you
can find plastic, cardboard
(USEPA 2005), packaging material, and paper, and bio-hazardous,
divided in two different types;
infectious or regulated waste (10%) as sharps, plastic
disposables, liquid waste, blood and blood
products, pathological waste (USEPA 2005) and non-infectious
waste (5%) as discarded glass,
chemical waste, incinerated waste, and radioactive waste (Razdan
and Cheema 2009; and Radha
et al. 2009).
The waste produced in the course of health-care activities
carries a higher potential for
infection and injury than any other type of waste by its
inadequate and inappropriate handling
causing serious health consequences and a significant impact on
the environment (Katoch 2007).
This waste should be classified according to source, typology
and risk factor associated with
handling, storage and ultimate disposal. While some hospitals or
pathological laboratory waste
may contain toxic chemicals, like mercury, xylene and formalin
(Dwivedi et al. 2009), requiring
special treatment as incineration or even hazardous waste
landfill facilities, the same may occur
to the waste produced by environmental pollution caused by:
spills during the industrial
production process, disposal of toxic compounds or excessive
treatment of agricultural surfaces
also disposed in landfill.
The industrial wastes can be comprised of organic compounds such
as aliphatic and
aromatic hydrocarbons, TPHs, derived from petroleum, charcoal
and wood, as well as natural
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26
products, halogenated solvents, pesticides, herbicides and
explosives (Csutak et al. 2010).
Intensification of agriculture and manufacturing industries has
resulted in increased release of a
wide range of xenobiotic compounds to the environment (Kumar et
al. 2011). For instance,
PAHs are a class of organic compounds that consist of two or
more fused benzene rings and/or
pentacyclic molecules arranged in various structural
configurations, highly recalcitrant due to
their hydrophobicity and low water solubility, ubiquitous in the
natural environment, which
originate from two main sources: natural (biogenic and
geochemical) and anthropogenic, major
source of environmental pollution (Bamforth and Singleton 2005).
These compounds naturally
occur in fossil fuels such as coal and petroleum, but are also
formed during the incomplete
combustion of organic materials such as diesel, wood and
vegetation, widely distributed in soils
and sediments, groundwater and the atmosphere (Bamforth and
Singleton 2005). Persistence of
PAHs in the environment depends on a variety of factors, as its
chemical structure, concentration
and dispersion, and bioavailability of the contaminant (Bamforth
and Singleton 2005). PAHs
have five fates in the environment; volatilization, leaching,
degradation, bioaccumulation and
sequestration (Maiti et al. 2012). The pollution caused by TPHs
compounds and their derivatives
is considered the most prevalent and worldwide environmental
contamination adversely affecting
human health along with a threat to environment (Kristanti et
al. 2011). Reason to say the excess
loading of hazardous waste has led to scarcity of clean water
and disturbances of soil thus
limiting crop production (Kumar et al. 2011).
TPHs are released into the environment through accidents, as
managed releases, or
unintended by-products of industrial, commercial or private
actions. Consequently, there is a need
to understand the changes that may occur over time in the
composition of hydrocarbons found in
soil, water, or air in order to assess public health issues for
TPH. Continuous spills or prolong
history of disposal at specific sites can lead to concerns; oil
dumped onto soils can saturate the
soil matrix, affecting its use for agricultural purposes. The
goals of the ecosystems’
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decontamination are recovery of soil health and fertility,
detoxification of ground water, re-
utilization of wastewater, removal of negative effects on human
and animal health, and
production of healthy air by means of bioremediation
techniques.
Section II. Bioremediation
Bioremediation is the elimination, attenuation or transformation
of polluting or
contaminating substances by use of biological processes (Shukla
et al. 2010). This process is an
interesting alternative for restoring the ecological equilibrium
in polluted environments through
immobilization, chemical transformation and mineralization
(Robertson et al. 2007). It involves
mainly non-invasive technologies with rather low costs and less
disruption of the contaminated
environment, with a high public acceptance, carried out on site
(Shukla et al. 2010) if compared
to other remediation technologies (Rigas et al. 2008) with only
rarely the addition of some
degradation enhancers (Csutak et al. 2010).
It is based on biodegradation processes related to microbial
population dynamics in soil
or water and its ability to consume xenobiotics as carbon source
(Csutak et al. 2010). The clean-
up of contaminated environment by means of exploiting the
diverse metabolic activities of
microorganisms is achieved by converting the contaminants to
harmless products as carbon IV
oxide and water, or by conversion into microbial biomass (Rigas
et al. 2008: and Ejoh et al.
2012).
There exist many techniques of dispersal, collection, removal,
landfill disposal and
incineration that simply dilute or sequester the contaminants or
transfer them to another
environmental medium (Rockne and Reddy 2003). In contrast,
bioremediation can be regarded
as a more effective and environmentally friendly strategy since
it results in the partial or complete
biotransformation of organo-xenobiotics to microbial biomass and
stable, innocuous end
products. It is a technique where biological treatments are
used, for the clean-up of hazardous
chemicals in the environment, to transform and/or degrade toxic
compounds or otherwise render
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28
them harmless (Vidali 2001; and Bennet et al. 2002), to disarm
noxious chemicals without
forming new toxins, treat contaminants on site with relatively
little disturbance to the
contaminated matrix (Head 1998).
The acceptance of bioremediation as a viable clean-up strategy,
however, in many cases
also depends on cost (cannot be more expensive than existing
chemical and physical treatments).
As a biological remediation alone or in combination with other
methods, it has gained an
established place as a soil remediation technology (Rockne and
Reddy 2003). This technique can
be applied for the complete destruction of a wide variety of
contaminants (Rigas et al. 2008) such
as industrial wastes (solid and liquid), municipal/urban wastes
(sewage), mining wastes
(including effluents containing heavy metals, etc), chemical
spills and hazardous wastes (Sen and
Chakrabarti 2009).
Bioremediation processes use biological agents, mainly
microorganisms (yeast, fungi or
bacteria) to clean-up contaminated soils and water. These
microorganisms are most important for
reclamation, immobilization or detoxification of metallic
pollutants (Gadd 2010), by using the
contaminants as nutrient or energy sources (Shukla et al. 2010;
and Kumar et al. 2011). The use
of living organism, microorganisms, and their enzymatic set is
considered an effective
remediation technology for the partial or total recovery of
polluted sites (Rao et al. 2010). Usually
bioremediation systems run under aerobic conditions, if the
process runs under anaerobic
conditions it may permit microbial organisms to degrade
otherwise recalcitrant molecules (Shukla
et al. 2010).
For instance, the bioremediation process to degrade PCBs (Figure
4) needs two steps;
dechlorination, mediated by anaerobic microorganisms (Borazjani
et al. 2005), and oxidative ring
cleavage, using aerobic organisms contained within the Earth’s
crust (De et al. 2004). Attributes
that can affect bioremediation process are superior growth
rates, competitive ecological strategies
and tolerances to high contaminant concentrations (Lamar et al.
1999). The types of
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29
microorganisms present stimulated by supplementing nutrients
(nitrogen and phosphorous),
electron acceptors (oxygen), and substrates (methane, phenol,
and toluene), soil structure, pH,
moisture, temperature, and introducing microorganisms with
desired catalytic capabilities (Shukla
et al. 2010) are means that can enhance microbial degradation
(Sen and Chakrabarti 2009) and,
eventually, control the time other contaminants as PAHs persist
in the environment (Bamforth
and Singleton 2005).
Figure 4. Summary of different bioremediation strategies for
typical hazardous wastes (adapted
from Brar et al. 2006).
Section III. Microorganisms in Bioremediation
The origins and sources of pollution are different: industrial
activities as mining and
metal processing, petrochemical and industrial complexes,
industry effluents, chemical weapons
production, pulp and paper industries, dye industries and
industrial manufacturing; and
anthropogenic activities as traffic, agricultural activities,
and others (Rao et al. 2010). Population
increase also impacts on the environment when using natural
resources, producing wastes,
causing environmental stress as loss of biodiversity, and
negative effects on air, soil and water
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30
pollution. These pollutants can affect the health of humans,
animals and the environment as
inhibit respiration, provoke reduced reproduction of fish-eating
birds, and even, contribute to the
birth of premature babies or children with genetic defects as
downs syndrome, anencephaly, and
spina bifida (Rao et al. 2010). Increase in contaminated sites
poses major environmental and
human health problems so there exists a need to implement
decontamination strategies mandatory
in order to properly decontaminate the environment (Rao et al.
2010).
Substances with high polluting potential are present in the
environment and affect soil,
sediments, water, air, microbial organisms, plants, animals, and
humans (Rao et al. 2010). These
substances may be distributed in one or all environmental
compartments not only as mixtures of
different organic compounds but also of organic and inorganic
independent chemicals (Rao et al.
2010). The use of microorganisms, during the remediation
process, is the most effective method
for dealing with widespread pollution (Tachibana et al. 2005;
Miyoshi et al. 2005; Tachibana et
al. 2006; and Tachibana et al. 2007). The effectiveness of
bioremediation process is often a
function of the microbial population or consortium and how it
can be enriched and maintained in
an environment (Márquez-Rocha et al. 2001). In most cases, the
treatment of all contaminated
environment has involved bio-stimulation, addition of nutrients
to stimulate the spontaneous
enrichment of the indigenous hydrocarbon oxidizing microbial
population based primarily on
their xenobiotic-degrading abilities, or bio-augmentation
containing a consortium of
microorganisms and inorganic nutrients, nitrogen, phosphate and
potassium (NPK) (Sharma and
Rehman 2009), with superior pollutant-degrading abilities that
may confer with exceptional
bioremediation performance (Lamar et al. 1999).
These transformations by microorganisms involve a complete
destruction or
immobilization of contaminants instead of transfer from one
environment to another as does
occur by extraction or incineration, which entails the transfer
of pollutant from soil to atmosphere
(Sharma and Rehman 2009). The ex-situ treatments involve the
physical removal of the
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31
contaminated matrix in the terrestrial ecosystem while the
in-situ treatments propose a relatively
low cost and ecologically friendly procedure on site for the
ability to re-use the land, providing
for a less toxic soil contamination using either the
bio-stimulation or the bio-augmentation
microorganism process.
Section IV. Soil in Bioremediation
In terrestrial ecosystems, soil is the major sink for metal
contaminants, while sediments
are the major sink for metals in aquatic systems affected
through run-off, leaching and transport
via mobile colloids (Gadd 2010). Metals are significant natural
components of all soils, present in
organic fractions, frequently in bound forms, with some metal
recycling occurring as a result of
organic matter degradation. Their presence in the mineral
fraction constitutes a pool of
potentially mobile metal species, many essential nutrients for
plants and microbes, and important
solid components, with a fundamental effect on soil geo-chemical
processes (Table 2), as occur
with clays, minerals, iron and manganese oxides (Gadd 2010).
Soil is “the biogeochemical
engine of Earth’s life support system” (Valentín et al. 2013).
It provides us with food, fodder,
fibre and fuel, readily rateable agriculture and forestry goods,
delivers ecosystem services not
easily traded in markets (Valentín et al. 2013). Life-supporting
functions include, recycling of
carbon and essential nutrients of all living materials,
filtering and storage of water, regulation of
the atmosphere and biological control of pests among others.
Continuous urbanization,
desertification intensified by the global change and
short-sighted agricultural practices threaten
the natural soil capital overall affecting the food safety and
agriculture sustainability for our
future generations.
The soil possesses properties as color, structure, texture and
pH with positive influence in
the bioremediation techniques. For instance, the color in soil
provides important clues about
organic matter, drainage, and other soil conditions. A darker
color can indicate more organic
matter is present compared to soil of a lighter color. Often the
surface horizon, called the
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32
epipedon, has a darker color than the subsoil due to higher
organic matter content. There are six
basic types of soil structure: platy, prismatic, blocky,
granular, loose structure, and compacted
structure but not necessarily one will observe these exact forms
in the field. For the composition
of the soil we consider the texture as the relative proportion
of sand, silt and clay particles where
the ones with moderate amount of each of the above are called
loams. There are 12 soil texture
classes: sand (S), loamy sand (LS), sandy loam (SL), loam (L),
silt loam (SiL), silt (Si), sandy
clay loam (SCL), clay loam (CL), silty clay loam (SiCL), sandy
clay (SC), silty clay (SiC), and
clay (C) (Staff 1993). Finally, the pH is determined to measure
how acidic (pH7) the soil is.
Table 2. Environmental factors and optimum condition for
microbial activity for soil
bioremediation (adapted from Shukla et al. 2010).
Environmental Factor Optimum conditions Condition required
for microbial
activity
Available soil moisture 25-85% water holding
capacity
25-28% of water
holding capacity
Oxygen >0.2 mg/L DO, >10% air-
filled pore space for
aerobic degradation
Aerobic, minimum
air-filled pore space
of 10%
Redox potential Eh > 50 mill volts -
Nutrients C:N:P= 120:10:1 molar N and P for microbial
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ratio growth
pH 6.5-8.0 5.5 to 8.5
Temperature 20-30ºC 15-45ºC
Contaminants Hydrocarbon 5-10% of
dry weight of soil
Not too toxic
Heavy metals 700 ppm Total content
2000ppm
Type of soil Coto-clay- Sand/Silt/Clay:
35:19:46
Low clay or silt
content
As soil ages biological processes increasing the nitrogen
contents, as leaching will reduce
phosphorous and become more acidic, will be distinctive in the
layers (Plaster 2003) determined
by the soil properties. There are five layers known as master
horizons, O, A, E, B, and C.
The O-horizon is an organic layer made of wholly or partially
decayed plant and animal
debris (undisturbed soil). This is the uppermost layer and is
usually found only in areas that have
some sort of permanent vegetation. It is a layer of plant litter
lying on the surface of the mineral
soil where considerable decomposition or organic matter takes
place, giving its characteristic dark
color.
The A-horizon, known as topsoil, is the surface mineral layer
where organic matter
accumulates, and leaches clay and iron material (eluviation)
down to other layer while sand
remains. When present, it lies beneath the O-horizon and is
darker than the underling horizons
(although not as dark as the O) due to accumulation of organic
matter in the soil surface.
Leaching is most intense in the soil surface and causes solutes
to move down the profile to the
underlying horizons.
The E-horizon, is the greatest eluviation zone, it possesses
leached clay, chemicals an