The Egyptian Journal of Hospital Medicine (Jan. 2016) Vol. 62, Page 109 - 126 109 Received: /12/2015 DOI : 10.12816/0021420 Accepted: 25/12/2015 INTRODUTION Follow fungi in desert region the strategy of fungus strain and representing growth of stressful environments, lack of food and low humidity, drought and high temperature or osmophilic [ 1 ] . Organisms living in environments with high concentrations of salts are challenged by osmotic stress and by the toxicity of specific ions [2] . Most fungi differ from the majority of halophilic prokaryotes . [3] they tend to be extremely halotolerant rather than halophilic and do not require salt to the survival, . [4] and especially the growth of microorganisms in highly saline environments requires numerous adaptations , [5] . The fungal cell wall is a supramolecular structure that offers strength to the cells, determines their shape, protects them against mechanical damage and mediates the cell-to-cell communication and their interaction with the environment. Physical and biological properties of fungal cell walls are determined by the composition and the arrangement of their structural components. [6] The fungal cell wall is the first line of defense against environmental stress; therefore, adaptation at the cell wall level is expected to have one of the most important roles for successful growth at a highly saline [7] The cell wall is essential for maintaining the osmotic homeostasis of cells, since it protects them against mechanical damage as well as high concentrations of salts. [8] Its balance between a rigid and a dynamic structure influences the shape of cells . [9] and enables growth and hyphal branching . [10] Some studies have focused on the role of the fungal cell wall in chemical sensing and processing of environmental signals that control growth and cell morphology of microorganisms and synthesis and secretion of extracellular enzymes. ,[11], [12], & [13] Little is known about their mechanisms of adaptation to high salinity. To investigate the effects of low and high NaCl concentrations on cell morphology, with particular emphasis on cell wall ultrastructure. [14] The dominant representatives and the most thoroughly investigated halophilic fungi in hypersaline waters of the salterns are the black yeasts, [15] and particularly the model organism Hortaeawerneckii. [16] An important level of adaptation of the black yeasts to high salinity is seen in their extremophilicecotype , which is characterized by a special meristematic morphology and changes in cell wall structure and pigmentation . [17] This work aims at investigating the effect of salt stress on growth of some halotolerant fungal isolates, also representing the effect of salt stress on their morphology by (SEM). Sodium Chloride Stress Induced Morphological Changes in Some Halotolerant Fungi Mona S. S. Al Tamie Qassim University – College of Science Email: [email protected]ABSTRACT Materials and methods: Nine fungal isolates namely Emericill anidulans, Mucor racemosus , Alternaria pluriseptata Penicillium canescens, Syncephalastrum racemosum, Aspergillus fumigatus, Alternaria chlamydospora, Aspergillus parasiticus and Ulocladium atrum were isolated from AL – SHEGA area at AL- QASSIM region. Results: The influence of different sodium chloride concentrations on the growth rate, morphological and ultrastructure were studied. Considerable differences in their growth rate and morphology were detected on medium containing different concentrations of sodium chloride (NaCl). Low growth rates were obseved on high NaCl concentrations . At 15 % NaCl, low growth of Emericill anidulans, Penicillium canescens, Syncephalastrum racemosum, Aspergillus parasiticus and Mucor racemosus was detected , whereas all fungal isolates were failed to grow at 20% NaCl . Scanning Electron Microscope (SEM) revealed that all fungal asexual reproduction organs were metamorphosed at higher NaCl concentration, fungal heads and sporangia were speculated or elongated. Sporangiophores and conidiophores were shortened and dwarfed ,little number of conidia or spores were detected. Key words : halotolerant fungi ,salt stress ,SEM.sodium chloride, morphology
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The Egyptian Journal of Hospital Medicine (Jan. 2016) Vol. 62, Page 109 - 126
109
Received: /12/2015 DOI : 10.12816/0021420 Accepted: 25/12/2015
INTRODUTION
Follow fungi in desert region the strategy of
fungus strain and representing growth of stressful
environments, lack of food and low humidity,
drought and high temperature or osmophilic [1].
Organisms living in environments with high
concentrations of salts are challenged by osmotic
stress and by the toxicity of specific ions [2]
.
Most fungi differ from the majority of halophilic
prokaryotes .[3]
they tend to be extremely
halotolerant rather than halophilic and do not
require salt to the survival, .[4]
and especially the
growth of microorganisms in highly saline
environments requires numerous adaptations,
[5].
The fungal cell wall is a supramolecular structure
that offers strength to the cells, determines their
shape, protects them against mechanical damage
and mediates the cell-to-cell communication and
their interaction with the environment. Physical
and biological properties of fungal cell walls are
determined by the composition and the
arrangement of their structural components.[6]
The fungal cell wall is the first line of defense
against environmental stress; therefore,
adaptation at the cell wall level is expected to
have one of the most important roles for
successful growth at a highly saline [7]
The cell wall is essential for maintaining the
osmotic homeostasis of cells, since it protects
them against mechanical damage as well as high
concentrations of salts.[8]
Its balance between a
rigid and a dynamic structure influences the
shape of cells .[9]
and enables growth and hyphal
branching .[10]
Some studies have focused on the role of the
fungal cell wall in chemical sensing and
processing of environmental signals that control
growth and cell morphology of microorganisms
and synthesis and secretion of extracellular
enzymes.,[11], [12], & [13]
Little is known about their mechanisms of
adaptation to high salinity. To investigate the
effects of low and high NaCl concentrations on
cell morphology, with particular emphasis on cell
wall ultrastructure.[14]
The dominant representatives and the most
thoroughly investigated halophilic fungi in
hypersaline waters of the salterns are the black
yeasts, [15]
and particularly the model organism
Hortaeawerneckii.[16]
An important level of adaptation of the black
yeasts to high salinity is seen in their
extremophilicecotype , which is characterized by
a special meristematic morphology and changes
in cell wall structure and pigmentation .[17]
This work aims at investigating the effect of salt
stress on growth of some halotolerant fungal
isolates, also representing the effect of salt stress
on their morphology by (SEM).
Sodium Chloride Stress Induced Morphological Changes in Some Halotolerant
Aspergillu sparasiticus ( N.o 8) and Ulocladium atrum ( No.9).
Mona Al Tamie
117
Table 3: Scanning Electron Microscope of isolated fungi at different concentrations of sodium chloride
and on sodium chloride free medium.
concentrations of
NaCl % (w/v) Scanning Electron Microscope of isolated fungi
0 % NaCl
1) Emericillanidulans
Heads are surrounded completely by conidia .
5% NaCl
The globosely heads shrunken appeared spatulas to some extent the globosely conidia changed and
reduced in No.
10% NaCl
Heads completely shrunken became rode in shape, little conidia appeared
Sodium Chloride Stress…
118
0 % NaCl
2) Mucor racemosus
Sporangiophores and sporangia appearednormally. Columella appeared obovate
5% NaCl
Sporangia are shrunken , spores rare
10% NaCl
Sporangiophoreswere dwarfed. Sporangia are shrunken, spores rare
Mona Al Tamie
119
0 % NaCl
3) Alternaria pluriseptata
Long conidiophores with chains of conidia with terminal peach
5% NaCl
Long conidiophores became shorter with chains of swollen conidia with rounded terminal
10% NaCl
Conidiophores became drastic with clusters of swollen conidia with rounded terminal or one
swollen conidium
Sodium Chloride Stress…
120
0 % NaCl
4) Penicillium canescens
Conidiophores heavily branching,metulae and phialieds carrying chains of conidia
5% NaCl
Branching of conidiophores was less to some extent metulae and phialieds are carrying smaller No.
of conidia
10% NaCl
Branching of conidiophores was less to some extent metulae and phialieds are carrying smaller No.
of conidia or no conidia
Mona Al Tamie
121
0 % NaCl
5) Syncephalastrum racemosum
Long sporangiophores with terminal vesicle which forms merosporangia all over its surface.
5% NaCl
Sporangia are smaller in size carrying smaller No of spores to some extent
10% NaCl
Sporangia size were very small sporangiospores were less than before. Drastic action appeared on
sporangiophores
Sodium Chloride Stress…
122
0 % NaCl
6) Aspergillus fumigates
Flask-shaped vesicle carrying sterigmata long chains of conidia.
5% NaCl
Flask-shaped vesicle became longitudinal with swollen sterigmata carrying little No of conidia
10% NaCl
Vesicles became longitudinal and drastic with drastic (to some extent ) sterigmata carrying little No
of shrunken conidia
Mona Al Tamie
123
0%
NaCl
7) Alternaria chlamydospora
Conidia and conidiophores are appeared normally with some chlamydospores
5%
NaCl
Conidia and conidiophores are enlarged clusters of conidia appeared.
10%
NaCl
Conidia are enlarged while conidiophores are appeared fine covered with sheath of salt, conidia
reduced in No.
Sodium Chloride Stress…
124
0 %
NaCl
8) Aspergillus parasiticus
Flask shape heads covered with sterigmata on long conidiophores
5%
NaCl
Flask shape heads became triangle covered with sterigmata on long conidiophores carrying smaller
No of conidia. All the fungus covered with sheath of salt
10%
NaCl
Flask shape heads became triangle or rounded covered with sterigmata or naked carrying smaller
No of conidia .All the fungus covered with sheath of salt.
Mona Al Tamie
125
0% NaCl
9) Ulocladium atrum
Conidia varicose, sometimes ellipsoidal with one or more transverse and longitudinal septa but
most common spherical or subspherical
5% NaCl
Spherical and ellipsoidal smooth conidia without septa
10%
NaCl
Ellipsoidal and longitudinal conidia without septa.Hyphae covered with sheath of salt
Sodium Chloride Stress…
126
Figure1: Influence of different NaCl concentrations on the growth of fungal isolates The fungal isolates as follow: Emericilla nidulans ( No.1) ; Mucor racemosus ( No.2) ; Alternaria