Environmental Microbiology Lecture 1

8/13/2019 Environmental Microbiology Lecture 1

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Plant and Animal associationsSubstances which make up living material are:

Carbon Hydrogen Oxygen Sulfur Phosphorous Nitrogen

Potassium Iron Sodium Calcium Magnesium

With the primary being

CarbonHydrogenOxygenNitrogen

SulfurPhosphorous

**An organic compound always

contains carbon and hydrogen**

The most significant effects of microorganismson earth is their ability to recycle the primaryelements that make up all living things(especially C / O / N)

These elements occur in different forms

Different forms of carbon and nitrogen areneeded as nutrients by different types oforganisms


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The most important aspects of microbialmetabolism that are involved in the cycleof nutrients are: Primary production Decomposition or Biodegradation Nitrogen Fixation Oxygenic Photosynthesis

Primary Production

Photosynthesis Organisms which take up CO2 in the air and

convert it to organic material (CO2 fixation) This accounts for a large portion of available

organic carbon available for synthesis of cellmaterial

Examples of carbon fixers are planktonic algae andcyanobacteria which are responsible for approximately ! of the primary production on earth.

Planktonic algae are

Unicellular organisms which float in thewater and provide the source of carbon

from which aquatic life is derived


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Cyanobacteria

Aquatic and photosynthetic

Small, unicellular Grow into colonies large enough to see Oldest known fossils

Decomposition or biodegradation

Breakdown of complex organic material to formsof carbon that can be used by other organisms

No naturally occuring organic compound existsthat can not be broken down by microbes

Some synthetic compounds like teflon,styrofoam, plastics, pesticides and insecticidesare broken down slowly or not at all

Through the metabolic processes of respirationand fermentation organic molecules eventuallybreak down to CO2 which cycles back to theatmosphere.

Examples of this use: Waste treatment Compost Sewage treatment


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Nitrogen Fixation

Process used by some bacteria that removes N2from the atmosphere and converts it toammonia for use by plants and animals

Nitrogen fixation also results in soilreplenishment by agricultural processes

Some bacteria have symbiotic associations withplants

Other nitrogen fixers are free living in both soiland aquatic habitats

Oxygenic Photosynthesis

Occurs in plants, algae and cyanobacteria Results in the production of O2 in the

atmosphere 50% of the oxygen on earth is produced

by photosynthetic microorganisms (algaeand cyanobacteria

The cyanobacterium Synechococcus is aprimary component of marine andfreshwater plankton

This unicellular prokaryotic is involved in

primary production, nitrogen fixation andoxygenic photosynthesis, participating inthe cycles of carbon, nitrogen and oxygen


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Heterocyst Specialized nitrogen fixingcells formed by some filamentouscyanobacteria ie. Anabaena

Harmful Effects of Microbes

The primary harmful effects of microbeson our existence and civilization is thatthey are a cause of disease in animals andcrops and they are agents of spoilage anddecomposition of our foods

Microbes cause infectious disease Historically, infectious diseases are the most

significant cause of death in humans Until the beginning of the 20 th century it is

estimated that more than ! of the people

that ever lived died from either small pox(virus) or malaria (protozoa) Bacteria has also been the cause of some of

the most deadly diseases and epidemics inhistory including: tuberculosis, typhus, plague,diptheria, typhoid fever, cholera dysenteryand pneumonia


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Green Algae: Are single celled and colonial, often

possessing 2 flagellates per cell

Possess 2 types of chloroplasts andprovide photosynthesis for many otherspecies in symbiosis

Harmless but can cause water to turn anunpleasant green colour

Green Algae

Pediastrum boryanum colonies

Blue Green Algae

Can be dangerous as some speciesproduce toxins as they reproduce

Are unique in that they can reproduceunder anaerobic conditions Exist in cellular arrangements or colonies


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Blue Green Algae

1 under microscope 2- blue green algae in rafts

Diatoms

Are single celled algae that possess atough silica covering

Exist as unicellular individuals or ascolonies in ribbons and spirals

They exist at the bottoms of ponds andare not motile

Diatoms


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Dinoflagellates Microscopic, unicellular, flagellated often photosynthetic

protists commonly regarded as algae

Characterized by a transverse flagellum that encircles thebody and a longitude flagellum orientated perpendicular tothe transverse flagellum.

This gives a distinctive spiral to their swimming motion Both flagella are inserted at the same point in the cell wall This point is slightly depressed and is called the sulcus In heterotrophic (ones that eat other organisms), this is

where a conical feeding structure (peduncle) is projected toconsume food

Dinoflagellates con t Possess a unique nuclear structure at some stage in their

life cycle a dinokaryotic nucleus (as opposed toeukaryotic or prokaryotic), in which the chromosomesare permanently condensed and attached to the nuclearmembrane

Cell walls of many dinoflagellates is divided into plates ofcellulose (armour) within vesicles known as thecae

These plates form a distinctive topology known astabulation which is the main means for classification

There exists some that are heterotrophic and autotrophicand some that are both

Form a significant part of primary planktonic productionin both oceans and lakes

Dinoflagellates are usually haploid and reproduceprimarily by fission

In unfavorable conditions, such as lack of nutrientsand / or light, some species can alter their life cycledramatically. Two vegetative cells can join togetherand enter a stage that is similar to hibernation, withthe organism taking in fats and oils.

Its shape gets fatter and the shell gets hard.Sometimes spikes are formed

When conditions revert to favorable, thedinoflagellates break out of the cell, quickly reformtheir individual thecae and return to the dinoflagellatesat the beginning of the process


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Dinoflagellates

Fission Asexual reproduction (only one parentis involved)

Does not involve meiosis or fertilization Primary form of reproduction for single celled

organisms such as bacteria and protists All prokaryotes reproduce asexually Asexual reproduction has short term benefits

such as when rapid population growth isimportant or in a stable environment

Sexual reproduction offers the advantage ofgenetic diversity and adaption to change

and continued again

Besides being primary producers (important partof the food chain), dinoflagellates are known forproducing nasty toxins, particularly when theyoccur in large numbers called Red Tides

Besides being bad for a large range of marine life,red tides can also introduce non-fatal or fatalamounts of toxins into animals (shellfish)that maybe eaten by humans who are also effected by thetoxins

Many of these toxins are quite potent and haveneurological effects


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Red Tide

Common name for a phenomenon known as analgal bloom

Event in which estuarine, marine or freshwateralgae accumulate rapidly in the water column

These algae or phytoplankton are microscopic,single celled protists that can form dense visiblepatches near the waters surface

Certain species contain photosynthetic pigmentsthat vary in colour from green, brown to red

Red Tide continued Caused by a species of dinoflagellates present in

significant numbers (thousands or millions of cells permilliliter), to turn the water a hue of red

The term Red Tide , is often used in the USA to describea particular type of algal bloom common to the easterngulf of Mexico. This is caused by a species ofdinoflagellate known as Karenia brevis and these bloomsoccur almost annually in waters along Florida s coast.

Also common on the northern east coast of the US andparticularly in the Gulf of Maine. This type of bloom iscaused by another species of dinoflagellate known as

Alexandrium fundyense . These blooms severely disrupt

fisheries of these waters as the toxins in these organismscause shellfish to become poisonous for humanconsumption

In 1972 a red tide in New England was causedby another species called Alexandriumtamarense

It isn t clear what causes red tides or why theyoccur where they do. It can be entirely natural

or a result of human activities The frequency and severity of algal blooms in

some parts of the world have been linked toincreased nutrient loading from human activities

Coastal water pollution and systemic increase insea water temperature have also beenimplicated as contributing factors


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Quorum Sensing Is the ability of bacteria to communicate and

coordinate behaviour via bioluminescence or asignaling moleculeThe consequences of quorum sensing is thecoordination of certain behaviour between bacteriabased on the local density of bacteria

Can occur between a single species of bacteria ordifferent species

Can regulate a host of different processes,essentially serving as a simple communicationnetwork

Protists:

Diverse group of organisms made up ofeukaryotes that cannot be classified into anyother Kingdoms such as fungi, animals or plants

They do not have much in common beside arelatively simple organization .

Either they are unicellular or multi-cellularwithout highly specialized tissues


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One example being the amoebae:

Euglenid The euglenids are one of the best-known groups of

flagellates, commonly found in freshwater rich in organicmaterial

Many have chloroplasts and produce energy throughphotosynthesis

Distinguished mainly by the presence of a pellicle whichis comprised of protein strips underneath the cellmembrane

Move by flagella Primary mode of nutrition is phagocytosis, mostly

bacteria and smaller flagellates

Euglenia


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IllnessesCiguatera

TrypanosomesCryptosporidium

Ciguatera Foodborne illness poisoning in humans caused

by eating marine species whose flesh iscontaminated with a toxin called ciguatoxin

Present in many microorganisms (particularly themicro-algae Gambierdiscus toxicus), living intropical waters

Accumulates in lower level organisms , resultingin higher concentrations of the toxins at higherlevels of the food chain (biomagnification)

Ciguatoxin is very heat resistant so ciguatoxinladen fish (moray eel, barracuda, parrotfish)cannot be detoxified by cooking

Ciguatera con t Symptoms include gastrointestinal and

neurological effects. Nausea, vomiting, and diarrhea usually

followed by headaches and muscle aches,numbness and hallucinations

Can be sexually transmitted andtransmitted to breastfed infants via breastmilk

Symptoms can last from weeks to yearsand there is no effective treatment orantidote


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Trypanosomes

Group of protozoa distinguished by having only a singleflagellum

Exclusively parasitic and found primarily in insects A few species have life cycles involving a secondary host,

which may be a vertebrate or plant. These include several species that cause major diseases

in humans Most notable being: trypanosomiasis (African Sleeping

Sickness and South American Chagas Disease). Theseare caused by species of Trypanosoma

Trypanosomes

Cryptosporidium

Is a protozoan pathogen of the Phylum Apicomplexa causing a diarrheal illness called cryptosporidiosis.

Other Apicomplexan pathogens include the malariaparasite Plasmodium , and Toxoplasm

Unlike Plasmodium, which transmits via a mosquito,Cryptosporidium does not utilize an insect and completesits lifecycle in a single host, resulting in cyst stages,which are excreted in feces and are capable oftransmission to a new host


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Cryptosporidium con t

Typically an acute short term infection, but can becomesevere in children and those with a compromisedimmune system

Parasite is transmitted by environmentally hardy cystthat once ingested, resides in the small intestines

Has a spore phase (oocyst) that can survive for lengthyperiods outside a host and can resist many commondisinfectants (notably chlorine based)

Water purification methods include coagulation followedby filtration or boiling

New methods include ultraviolet light and ozonation

CryptosporidiumLifecycle

Fungus

Any member of a large group ofeukaryotic organisms that include yeastsand molds as well as mushrooms

Hyphae Main mode of vegetative growth Classified as a kingdom separate fromplants and animals

Helpful decomposition, nutrient cycling,direct source of food, fermentation

Harmful food spoilage, pathogens


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More definitions:

Autotroph organism that producescomplex organic compounds from simple

inorganic molecules using light Heterotroph Take in autotrophs as food.

These include animals, most fungi as wellas most bacteria and protozoa

Environmental Microbiology Lecture 1

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