Microbial Diversity
Module – 2
Biology for Engineers
Microbiology:
The study of microorganisms.
Microorganisms: Small living organisms that generally
can not be seen with the naked eye.
Include:
Bacteria (Eubacteria, Archaebacteria, cyanobacteria)
Fungi (yeasts and molds)
Protozoa
Algae
Multicellular parasites
Also include nonliving infectious agents:
 Viruses
 Prions
Diversity of Microorganisms
I. Bacteria (Sing. Bacterium)
Small, single-celled (unicellular) organisms.
Procaryotes: “Before nucleus”.
Lack the following structures:
Nuclear membrane around DNA
Membrane bound organelles
Mitochondria
Chloroplasts
Golgi apparatus
Endoplasmic reticulum
Lysosomes
Kingdom Prokaryotae: Bacteria lack
nucleus and membrane bound organelles
Diversity of Microorganisms
I. Bacteria (Sing. Bacterium)
Include two groups:
Eubacteria: Peptidoglycan cell walls.
Archaebacteria: Lack peptidoglycan cell walls.
Shapes: Several forms:
Bacilli: Rod like. (Sing. Bacillus)
Cocci: Spherical. (Sing. Coccus)
Spiral: Corkscrew or curved
Square
Star shaped
Diversity of Microorganisms
I. Bacteria (Sing. Bacterium)
Divide by binary fission (not mitosis).
Source of nutrients varies:
Heterotrophs: Consume organic chemicals.
Autotrophs: Make their own food. Include photosynthetic
bacteria.
Motility: Many can “swim” by using moving
appendages:
Cilia: Small hair like structures
Flagella: Large whip like structures.
 Cyanobacteria are a group of photosynthetic, nitrogen fixing bacteria that live
in a wide variety of habitats such as moist soils and in water.
 free-living or form symbiotic relationships with plants or other marine
organisms or with lichen-forming fungi as in the lichen genus.
 unicellular to filamentous and include colonial species
 Aquatic cyanobacteria are known for their extensive and highly visible blooms
that can form in both freshwater and marine environments.
 Cyanobacteria have chlorophyll as well as a bluish pigment called phycocyanin
 “blue-green algae”
 Among the first photosynthetic organisms
 Because of their size, cyanobacteria are believed to be the most abundant
photosynthetic organisms in the ocean
 In addition to being free-living,
 Can do nitrogen fixation
Symbiotic Bacteria
 Many of the organelles found in eukaryotic organisms evolved
from symbiotic bacteria
 Examples of symbiotic bacteria include those involved in the
digestion of wood by shipworms, those responsible for
bioluminescence and those found in association with mussels,
clams and tubeworms that live around hydrothermal vents
Symbiotic Bacteria
Shipworms
(Teredo) are
actually
wood-eating
bivalve
molluscs!
http://www.divernetxtra.com/biolog/pics/0900flash1.jpg
Bacteria sheltered in lightemitting photophores of
flashlight fish
Tetrodotoxin produced by
bacteria in (immune)
pufferfish
bioweb.uwlax.edu/zoolab/lab-5a/mollusca-bivalvia-7.htm
Prokaryotes: Domain Archaea
 Archaea (Domain Archaea) are among the simplest, most
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primitive forms of life
Oldest fossils ever found (3.8 billion years old) appear similar to
Archaea
Archaea are prokaryotes, unicellular organisms that lack a
nucleus and other membrane-bound organelles
Anaerobic
Thought to have had an important role in the early evolution of
life
 Methanophiles (that produce methane gas)
 Extreme thermophiles (live in extremely hot temperatures)
 Extreme Halophiles (live in very high salt content)
Archea - Extremophiles
 Some groups of Archaea were
discovered only recently
 First in extreme environments on
land – hot sulfur springs, saline lakes,
and highly acidic or alkaline
environments
 “Extremophiles”
http://www.dpchallenge.com/image.php?IMAGE_ID=448561
Archaea
 Archaea were subsequently found in extreme marine
environments, such as in very deep water, where they survive at
pressures of 300-800 atmospheres
 Some archaea live at the high temperatures of hydrothermal
vents, and cannot grow in temperatures under 70-80°C (158176°F); 1 hydrothermal vent archaeum can live at 121°C
(250°F) – the highest of any known organism
Chemosynthesis
 Not all prokaryotic autotrophs derive energy from
photosynthesis
 Some bacterial autotrophs – called chemosynthetic – derive
energy not from light, but from chemical compounds
 Hydrogen sulfide (H2S) and other sulfur, nitrogen and iron
compounds provide energy to convert CO2 into organic matter
 Base of food web at hydrothermal vents
Evidence for life on Earth?
 Many of the harsh conditions which extremophiles require to
survive were characteristic of our early Earth
 Likely that Archaea evolved to dwell in such conditions billions of
years ago & survive today in similar (specific) environments
• The hot water emerging from hydrothermal vents is rich in
hydrogen sulfide (H2S) which is toxic to most organisms, but an
energy-rich molecule
• Water near the vents
contain so many microbes that they
cloud the water!
• Symbiotic and
• non-symbiotic
Eukaryotes: Domain Eukarya
 Eukaryotes (Domain Eukarya) possess a nucleus, a membrane
that encloses the DNA, in each of their cells
 While all prokaryotes (domains Archaea and Bacteria) are
uni-cellular, eukaryotes include both uni-cellular and multicellular organisms
 Kingdoms Protista, Fungi, Plantae, and Animalia
Microbial Eukaryotes
 Most microbial eukaryotes belong to the Kingdom
Protista
Diversity of Microorganisms
II. Fungi (Sing. Fungus)
Eucaryotes: “True nucleus”
DNA is surrounded by nuclear membrane.
Cells have membrane bound organelles: Mitochondria,
endoplasmic reticulum, etc.
Cells are larger than those of procaryotes.
May be unicellular or multicellular:
Unicellular: Yeasts
Multicellular: Molds, mushrooms
Do not carry out photosynthesis.
Must absorb organic nutrients from their environment.
Diversity of Microorganisms
II. Fungi (Sing. Fungus)
Source of nutrients varies:
Saprotrophs: Decomposers that feed on dead and
decaying matter. Most fungi are decomposers.
Parasites: Obtain nourishment by parasitizing live
animals and plants.
Cell wall made of chitin.
May reproduce sexually or asexually.
Diversity of Microorganisms
III. Protozoa (Sing. Protozoan)
Eucaryotes: “True nucleus”
DNA is surrounded by nuclear membrane.
Cells have membrane bound organelles and are larger than
those of procaryotes.
Unicellular
Kingdom Protista
Sexual or asexual reproduction
Classified based on locomotion:
Pseudopods: “False feet”. Cytoplasmic extensions.
 Example: Amoeba
Protozoa Belong to Kingdom Protista: Eucaryotic
Unicellular or Simple Multicellular Organisms
Diversity of Microorganisms
III. Protozoa (Sing. Protozoan)
Classified based on locomotion:
Flagella: Long whip like appendages.
Example: Trichomonas vaginalis, causes
trichominiasis, a sexually transmitted disease.
Cilia: Small hair like appendages
Nonmotile: Do not move in their mature
forms.
Example: Plasmodium spp., causative agent of malaria.
Diversity of Microorganisms
IV. Algae (Sing. Alga)
 Eucaryotes: “True nucleus”
 Photosynthetic: Important part of food chain because produce
oxygen and carbohydrates used by animals. Nearly all algae perform
photosynthesis using photosynthetic pigments
 Unicellular or multicellular
 Kingdom Protista
 As protists, algae are distinct from plants and lack specialized tissues, and
flowers
 They also lack true leaves, stems and roots
 Unicellular or multi-cellular
 Multicellular algae are seaweeds!
 Sexual or asexual reproduction
 Cell walls composed of cellulose
 Found in aquatic environments (oceans, lakes, rivers), soil, and in
association with plants.
Unicellular Algae: The Diatoms
 Diatoms are unicellular, although many species aggregate to
form chains
 Diatom cells are enclosed by cell walls made of silica; this glassy
shell or frustule consists of 2-tightly fitting halves
Diatoms
 Diatoms are very important primary producers in temperate and
polar regions
 Account for a large share of the organic carbon produced on
Earth
 Favorable environmental conditions (light and nutrients)
promote periods of rapid reproduction known as blooms
 The glass frustules of dead diatoms eventually settle to the sea
floor; diatomaceous ooze
Dinoflagellates
 Dinoflagellates are another important group of planktonic,
unicellular protists
 Two flagella; one wrapped along a groove along the middle of the
cell, the other trailing free
Dinoflagellates
 Dinoflagellates may be autotrophic, heterotrophic or both
(mixotrophic)!
 Nearly all dinoflagellates are marine
 Important primary producers, especially in tropical regions
 Some species release toxic substances and can cause harmful
“red tides”
 And some are bioluminescent
Dinoflagellates
 In addition to blooms of “red tide”, some dinoflagellates release
toxins responsible for open sores on fish, crustaceans and
bivalves
Zooxanthellae
• A group of dinoflagellates called zooxanthellae live in close
association with animals such as coral, sea anenomes, sponges
and giant clams
• Symbiotic: zooxanthellae photosynthesize within the body of an
animal host, releasing organic matter and receiving nutrients (in
the form of waste products) and shelter in return
• Loss of the colorful zooxanthallae is behind the phenomenon of
coral bleaching
 Other examples include chlorella, chlamydomonas.
 Mulicellular : Volvox
Diversity of Microorganisms
VI. Multicellular Animal Parasites
Eucaryotes: “True nucleus”
Multicellular animals, usually are visible to the naked
eye.
Microscopic during some stages of life cycle.
Spend part or all of their lives inside an animal host.
Helminths include:
Flatworms (Platyhelminths): E.g. Tapeworm
Roundworms (Nematodes): E.g. Ascaris, pinworm.
Diversity of Microorganisms
V. Viruses
Acellular infectious agents, not
considered living because they lack cells.
Obligate intracellular parasites: Viruses can
only reproduce by using the cellular machinery of
other organisms.
Simple structure:
Protein coat (capsid) with either DNA or RNA, but
not both.
May also have a lipid envelope.
Comparison of Cells and Viruses
Microbes are Essential for Life
on Earth: Have many important and
beneficial biological functions:
 Photosynthesis: Algae and some bacteria capture
energy from sunlight and convert it to food, forming
the basis of the food chain.
 Decomposers: Many microbes break down dead
and decaying matter and recycle nutrients that
can be used by other organisms.
 Nitrogen Fixation: Some bacteria can take
nitrogen from air and incorporate it into soil.
Important and beneficial biological functions of
Microbes:
 Digestion: Animals have microorganisms in their
digestive tract, that are essential for digestion and
vitamin synthesis.
 Cellulose digestion by ruminants (cows, rabbits, etc.)
 Vitamin K and B synthesis in humans.
 Medicine: Many antibiotics and other drugs are
naturally synthesized by microbes.
 Penicillin is made by a mold.
Importance of microbes in
Pharmaceutical industry
 Alexander Flemming in 1928 discovered Penicillin produced by a fungus ( P.
notatum) that kills bacteria. Thereafter many such antibiotics were discovered.
Antibiotics are natural or synthetic substances that inhibits the growth of other
organsims. These are the secondary metabolites produced by filamentous fungus
and bacteria classified as actinomycetes.
 Streptomycin (Streptomyces griseus)
 Erythromycin (Streptomyces eryhtreus)
 Chloramphenicol (Streptomyces venezuele),
 Bacitracin ( Bacillus subtilis)
 Polymixin B (B. polymixa)
 Chlorotetracycline (Streptomyces aureofaciens) –broad spectrum antibiotics
etc.
How are antibiotics discovered: by screening microbes from natural environment
and look for inhibition of growth of test bacteria. New substance is tested for
toxicity and is effectiveness in animals, before commercial production is
contemplated.
 Many vitamins can be obtained from microorganisms but the most
commercially cost-productive are vitamin B12, thiamine,
riboflavin and ascorbic acid. Bacteria of genera Bacillus,
Streptomyces, Pseudomonas and Propioni are grown on substrates such as
glucose or methanol, the latter two bacteria under anaerobic
conditions.
 Enzymes : Ex Streptokinase is a clot buster and Glucose oxidase
is used by diabetics in biosensors to measure blood glucose levels.
 Microorganisms are used in large scale manufacturing of vaccines
against diseases like influenza flu, polio, BCG etc.
 Citric acids : is used to preserve stored blood, tablets and
ointments. as an anti-foaming agent.
Important and beneficial biological
functions of Microbes:
 Pharmaceuticals & Genetic
Engineering: Recent advances allow us to
design recombinant microbes that produce
important products:
 Human growth hormone (Dwarfism)
 Insulin (Diabetes)
 Blood clotting factor (Hemophilia)
 Recombinant vaccines
Hepatitis A and B vaccines
 Human hemoglobin (Emergency blood substitute)
 Erythropoietin (Anemia)
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Important and beneficial biological functions
of Microbes:
 Medical Research: Microbes are well suited
for biological and medical research for several
reasons:
 Relatively simple and small structures, easy to study.
 Genetic material is easily manipulated.
 Can grow a large number of cells very quickly and at
low cost.
Short generation times make them very useful to study
genetic changes.
Important and beneficial biological functions of Microbes:
Food & Fermentation Industry:
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Microorganisms ferment various substances, usually carbohydrates, in nutrient media. They produce a variety
of chemicals (various alcohols, lactic acid, acetic acid, citric acid, gluconic acid, etc.) which are being recovered,
purified and sold.
Foods which are originated from animals are enzymatic ally processed by specific microorganisms resulting in
increase in their nutritive value. These foods are fermented foods like Yogurt, milk by products like cheese, sweet
chocolates and silage.eg Bacteria like Lactic acid bacteria are used in production of pure curd and other milk
products. Lactobacillus, Streptococcus and Leuconostoc bacteria metabolise sugars in the substrate and produce lactic acid.This
lowers the pH and inhibits the growth of other bacteria so preserves the food. It also alters the consistency,
texture and flavour by coagulating proteins.and used in preprartion of
•• yoghurt (milk)
•• sauerkraut(cabbage)
•• kimchi (vegetables)
•• salami (meat)
•• silage
lactobacilli such as Lactobacillus bufgariau, L. delbrueckii, etc., grow raipdly and convert the lactose
to the single end product, lactic acid. Lactic acid has many uses. It is used as an acidulant in confectionery,
fruit juices, and essences. It may be used in the curing of meat and in canned vegetable and fish products.
Lactic acid is used in various chemical industries. The lactates also have important uses. Calcium lactate is used
in baking powders and bread, and in the treatment of calcium deficiency. Iron lactate is used in the treatment of
anemia.
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Production of vinegar (acetic acid) from alcohol (Acetobacter)The microorganisms that produce acetic
acid from ethyl alcohol are species of Acctobac.ct,—A. orkannt, A. orleansis, A.schutzenbachi, A.Aceti
and others. The biochemical reaction by which they form acetic acid from ethanol is as follows ::2CH3 CH2OH + 02  2CH3CHO + 2H2O
2CH3 CHO + O2  2CH3COOH
Some of the Acelobacter species do not stop With acid production but continue the oxidation
to carbon dioxide.
CH3COOH + O2  2CO2 + 2H2O
Thus selection of proper organisms is important for vinegar fermentation. The organisms
should carry the reaction as near to completion without destroying acetic acid by oxidation. In
addition they must be tolerant to ethanol.
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Enzymes. A number of microbial,enzymes have industrial applications, and are produced on a large scale.
Pectinases from Aspergillus swentii Used as clarifying agents in fruit –juice.Amylases from Aspergillus oryzae in
beer production etc
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Gibbrellic acid –a plant growth hormone produced from Fusarium moniliforme : used in germination of barley
to produce malt which has many applications in food industry
Citric acids (Aspergillus swentii ) :used in many food products This is a primary metabolite used in the food and
drinks industry as a flavour enhancer for marmalade, fruit juice and ice cream.
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 SCP are the dried cells of selected micro-organisms such as algae, yeast,
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bacteria molds, and higher fungi, that can be used as rich protein sources
to humans and animals.
Ex algae such as Scenedesmus, Spirulina, Chlorella etc, and
bacteria such as Rhodopseudomonas, Bacillus and Azatobacteria
Yeasts belonging to the genera Saccharomyces, Candida and Kluyveromyces.
Fungus like mushroom is today being used as source of nutrition as well as medicine.
Bacteria like Bifidobacteria are being used in food industry as probiotics which helps in
curing of diseases of digestive systems and intestinal disorders.
Amino acids : Many are used in the food and beverage industries to enhance flavours
(glutamic acid is used to make sodium glutamate); as antioxidants (cysteine, Ltryptophan and L-histidine) and as sweeteners (aspartame made from aspartic acid and
phenylalanine). Proline is used in cosmetics.
Various types of bacteria, including E. coli, Lactobacillus, Klebsiella,Corynebacterium and
Bacillus genera are used.
Alcoholic beverages (Wine, beer, rum, whiskey)
 beer :Anaerobic fermentation. Uses strains of yeast such as
Saccharomyces cerevisiae and maltose obtained from malted barley
as the substrate. Metabolites other than ethanol impart
distinct flavours to the brew.
 wine : Anaerobic fermentation. Uses strains of yeast that
may occur naturally on the grapes or be added to give better
consistency of quality. A second, slow fermentation takes
place during the ageing process. Other metabolites besides
ethanol give distinct aromas and flavours.
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Beer. is made by the yeast fermentation of grains to ethanol and carbon dioxide.
There are five major steps in the manufacture of beer or ale from grain.
These are malting, mashing, 'fermenting, maturing, and finishing.
Malting and mashing are concerned with the conversion of starch into fermentable
form such as maltose or glucose.
The chief raw material is malt, which is germinated barley that has been dried and
ground. It contains stanch, proteins, and high concentration of amylases and
proteinases.
Amylases convert the starch into fermentable sugar. Mold amylase derived from
Aspergillus oryzae is sometimes used for the same purpose.
Ground malt is mashed in warm water to bring about the digestion of starch and
proteins.
The aqueous extract contains dextrins, maltose, and other sugars, protein
breakdown products, minerals and various growth factors. This is a rich nutrient
medium and is called beer wort.
The beer wort is filtered and hops are added, Hops are the flowers of Humulus lupulus.
They are added for flavour, colour, and for aroma and for mild antibacterial activity
to prevent the growth of spoilage bacteria.
 A large inoculum of selected strain of Saccharomyces
cerevisiae is added to the wort to bring about a
vigorous fermentation. Yeasts are classified as 'top
yeasts' or 'bottom yeast*.Top yeasts float on the
surface of a fermenting mixture and are employed
in making ale. Bottom yeasts settle in the
fermentation tank and are used in making beer.
 Beer fermentation takes place at 6 to 12°C., whereas
ale fermentation is complete in five to seven days at
14 to 23°C.
 alcoholic content of beer is between 3 to 6 percent,
that of ale is somewhat higher.
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Aging: The fermented wort is refrigerated at 0°C for two weeks to several months to
remove the harsh flavour and other undesirable characteristics. Some of the
harshness attributed to higher alcohols disappears as they are oxidized or esterified
during aging.
Finishing process consists of carbonation, cooling, filtering and dispensing into
barrels, bottles, and cans. Bottled or canned beer is usually pasteurized at 60°C for 20
minutes to kill yeasts and other microorganisms. As an alternative, the beer may be
passed through a filter to remove microorganisms, and then aseptically dispensed
into sterile cans. The composition of beer is as follows :
Alcohol
3.8 percent
Dextrins
4:3 percent
Proteins
0.3 percent
Ash
0.3 percent
C02
0.4 percent
It also contains appreciable amounts of vitamins, particularly riboflavin. In addition,
there area number of minor constituents, some of which are important for flavour
and aroma.
Industrial alcohol
Ethyl alcohol can be produced by fermentation of any carbohydrate containing
a fermentable sugar, or a polysaccharide that can be hydrolysed to a fermentable sugar.
The equation that describes the net result of alcoholic fermentation by yeast is :
C6H12 O6 2C2H5OH + 2 CO2
It indicates that a sugar is the substrate and that the process is anaerobic.
Selected strains of Saccharomyces cerevisiae are commonly employed for fermentation.
the strain must have a high tolerance for alcohol, must grow vigorously and produce
a large quantity of alcohol.
In recent years the production of industrial alcohol by the fermentation process has
declined because of the-increased cost of raw materials and the rapid developments
of synthetic ethanol production
Role of microbes in Agriculture
 As insceticides: Bacillus thuringiensis produces a toxic crystal
during sporulation ,that kills certain insects (pest of crop plants)
such as
 The toxic cyrstal ia a protein that damages the digestive track of
larva as a result of which the larva dies. The protein is not toxic
for human and animals. The bacillus is sprayed on the plants during
growing season
 Example :
 Another bacterium that is used is B. popillae
 Transgenic plants are being created that express the gene coding for BT-
toxin ex BT-Toxin
The term 'Biofertilizer' itself means
'Live Fertilizer'.
 As Biofertilizers which are defined as biologically active
products or microbial inoculants of bacteria , fungi, and
algae. These can interact with Plants and are known to deliver
benefits including plant nutrition, disease resistance and
tolerance to adverse soil and environmental conditions.
 These organsim can be used as biofertilizer and thus are
environmental friendly.
 These can be sprayed on agricultural lan just like chemical
fertilzers.
 They increase the fertility of soil
• contain live or latent beneficial microbes which help to fix
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atmospheric nitrogen,
solubilize and mobilize phosphorus,
translocate minor elements (Zinc, Copper, etc.,) to the plants,
produce plant growth promoting hormones, vitamins, amino
acids and
control plant pathogenic fungi.
Extremely advantageous in enriching the soil fertility and
fulfilling the plant nutrient requirements by supplying the organic
nutrients through microorganism and their byproduct.
 N-fixing-Rhizobium, Azotobacter, Azospirillum,
 . Biofertilizers for rice crop: Azolla, Blue green Algae,
 Azospirillum
 . P-solubilizing and Mobilizing microorganisms:
 Bacteria and Fungi
 . Compost making microorganisms: Cellulotytic and
 lignolytic
• Biofertilizers do not contain any chemicals which are harmful to the
living soil.
• Biofertilizers are eco-friendly organic agro-input and more cost effective
than chemical fertilizers.
• Nitrogen fixation :Biofertilizers like Rhizobium, Azotobacter,
Azospirillum and blue green algae (BGA) are in use since long time ago.
• Azotobacter, Azospirillum is a free living bacteria, can be used with crops
like wheat, maize, mustard, cotton, potato and other vegetable crops.
• Rhizobium inoculant is used for leguminous crops fix atmospheric
nitrogen in the soil and makes it available to the plant. Found in
symbiotic relationship with leguminous plant such as beans , gram mung
groundnut, soybean etc (in root nodules) and increase the soil
productivity.
• Azollae,
a free-floating aquatic fern fixing atmospheric
nitrogen through the cyanobacterium. Anabaena azolla,
present in its dorsal leaves, is one of the potential
nitrogenous biofertilizers.
• Its high nitrogen-fixing capacity, rapid multiplication as also
decomposition rates resulting in quick nutrient release have
made it an ideal nutrient input in farming systems.
 Largely used in RICE cultivation as green manure.
Phosphorus solubilizer
.
 Bacteria- Bacillus spp
 . Fungi- Pencillium
 . Efficiency of bacteria is more than fungal strains.
 . Substitute 15-20 percent dose of phosphorus
 . Mechanism is by phosphatase production.
Phosphorus mobilizers
 Gigaspora, Acullospora are the important sp.
 . Phosphorus is being mobilized.
 . Increase the availability of P, Mg, Ca and Zn.
Sulphate solubilizers
 Acidophillic thiobacillus thiooxidans is capable of oxidising
elemntal sulphur which reults in production of water soluble
sulphate salts
 Faciltates reduction of soil pH also , converts non available
sulphur and sulphur related compounds into easily available
form to plants
fermentation
 Fermentation is a metabolic process that converts sugar to
acids, gases or alcohol. It occurs in yeast and bacteria, and
also in oxygen-starved muscle cells.
 The process is often used to produce wine and beer
 Also employed in preservation to create lactic acid in
sour foods such as pickled cucumbers, kimchi and
yogurt.
 During fermentation pyruvate is metabolised to various
different compounds.
 Louis Pasteur's finding showed that there are two types
of fermentation:
 alcoholic fermentation: and
 lactic acid fermentation:.
 alcoholic fermentation is the conversion of pyruvate into ethanol
and carbon dioxide (by the action of yeast)
Alcoholic Fermentation:
C6H12O6
2CO2 + 2C2H5OH
glucose
carbon dioxide
•provides 2 molecules ATP per glucose
•done by yeast
ethanol
Products of Alcoholic Fermentation
don’t drink alcohol
lactic acid fermentation, by the action of bacteria.
Homolactic fermentation is the production of lactic acid from
pyruvate;
Heterolactic fermentation is the production of lactic acid as well
as other acids and alcohols.
 Typical examples of fermentation products are ethanol, lactic acid,
and hydrogen.
 However, more exotic compounds can be produced by
fermentation, such as butyric acid and acetone.
 Industrial fermentation processes may be divided
into two main types, with various combinations and
modifications. These are
 batch fermentations and
 continuous fermentations.
 Batch fermentations
 A tank of fermenter is filled with the prepared mash of
raw materials to be fermented. The temperature and pH
for microbial fermentation is properly adjusted, and
occassionally nutritive supplements are added to the
prepared mash. The mash is steam-sterilized in a pure
culture process. The inoculum of a pure culture is added
to the fermenter, from a separate pure culture vessel.
Fermentation proceeds, and after the proper time the
contents of the fermenter, are taken out for further
processing. The fermenter is cleaned and the process is
repeated. Thus each fermentation is a discontinuous
process divided into batches.
 Growth of microorganisms during batch
fermentation confirms to the characteristic growth
curve, with a lag phase followed by a logarithmic
phase. This, in turn, is terminated by progressive
decrements in the rate of growth until the
stationary phase is reached. This is because of
limitation of one or more of the essential nutrients.
 Continuous fermentation
 In continuous fermentation, the substrate is added
to the fermneter continously at a fixed rate. This
maintains the organisms in the logarithmic growth
phase. The fermentation products are taken out
continuously. The design and arrangements for
continuous fermentation are somewhat complex.
 Aerobic fermentations
 A number of industrial processes, although called
'fermentations', are carried on by microorganisms
under aerobic conditions.
 In older aerobic processes it was necessary to furnish a
large surface area by exposing fermentation media to
air.
 In modern fermentation processes aerobic conditions
are maintained in a closed fermenter with submerged
cultures. The contents of the fermenter are agitated with
au impeller and aerated by forcing sterilized air.
 Anaerobic fermentations
 Basically a fermenter designed to operate under
micro-aerophilic or anaerobic conditions will be
the same as that designed to operate under aerobic
conditions, except that arrangements for intense
agitation and aeration are unnecessary. Many
anaerobic fermentations do, however, require mild
aeration for the initial growth phase, and sufficient
N agitation for mixing and maintenance of
temperature.
 Baking (Yeast):
Baked goods like bread rise because of the presence of yeast
as a raising, or leavening, agent. The most common yeast used
in breadmaking is Saccharomyces cerevisiae. It feeds on the
sugars present in the bread dough, producing the gas carbon
dioxide which is a byproduct of the fermentation. This forms
bubbles within the dough, causing it to expand. Other
ingredients in the mixture have an effect on the speed of the
fermentation – sugar and eggs speed it up; fats and salt slow
it down.
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Baker's yeast
The production of baker's yeast is the largest domestic use of a microorganism for food purposes.
Baker's yeast is a strain of Sacchawinyces certvisiae The strain of the yeast is carefully selected for
its capacity to produce abundant gas quickly, its viability during ordinary storage, and its ability
to produce desirable flavour. The organisms are mixed with bread dough to bring about vigorous
sugar fermentation. The carbon dioxide produced during the fermentation is responsible for
leavening or rising of the dough.
A pure culture of the selected strain of yeast is first grown in the laboratory and gradually built
up to larger and larger volume by transfer from the test tube to the fermenter tank. Great care is
taken to prevent contamination at any stage of development of the culture. During
manufacturing, the strain is inoculated into a medium which frequently contains molasses and
corn-steep liquor as sources of carbon, nitrogen, and mineral salts. The reaction of the medium is
adjusted to pH 4.4 to 4.6. The inoculated medium is incubated at a temperature of 25 to 26°C, and
is aerated during the incubation period. Yeasts oxidize sugars under aerobic conditions with the
liberation of energy. A large part of this energy is utilized for the synthesis of cell protoplasm.
The yeast cells multiply rapidly and exhaust the sugar supply within 10 hours.
At the end of incubation the yeast cells are removed from the fermented medium by
centrifugation, washed and mixed with starch or corn meal, and then being pressed into cake
form. Yeast cakes must be kept cool to preserve the cells and to prevent spoilage by other microorganisms. They may also be dried. Dried yeast remains viable for several months. Yeasts are rich
in vitamins and in most of the essential amino acids required by man and animals.
 Biological weapons or infectious agents (bacteria, virus,
fungi, protozoan etc.) used to intentionally inflict harm on
humans.
 The definition is extended to include biologically derived
toxins and poisons.
 Generally, the types of agents used as biological weapons
cause systemic diseases, hemorrhagic fevers, pneumonias, or
involve toxins and biological poisons.
What makes a good biological
weapon?
The microbes should be able to survive outside of the
body, the biological agent must virulent and lethal
The weapon should be quick-acting without a long lag
time between dispersal and illness.
The biological agent should be easily dispersed,
preferably as a powder, and should also be infectious
through person-to-person contact.
The agent should be easy to
weaponise?
grow in large quantities and not require
sophisticated equipment or training
The agent should also be inexpensive to grow in
quantity, especially for unfunded terrorists.
Ability to weaponize.
Because they are invisible, silent odorless
tasteless biological agents may be used as
an ultimate weapons easy to disperse and
inexpensive to produce
Advantages of Biologics As Weapons
 May be easier, faster to produce and more cost-effective than other
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weapons
Potential for dissemination over large geographic area
High morbidity and mortality
Creates panic
Person-to-person transmission possible (smallpox, plague, and viral
hemorrhagic fever)
Difficult to diagnose and/or treat
Domestic Biological Terrorism
• 1984
contaminate
Salmonella typhimurium in
salad bar with
Oregon
• 1992
Ricin attack planned by Minnesota militia
• 2001
Anthrax releases in FL, DC, NY, NJ
Biowarfare : Highest Concern CDC designated
“A” List of Biologic Agents
•Anthrax
•Plague
•Smallpox
•Botulism
•Tularemia
•Viral Hemorrhagic Fever
The “Top Four” Bioterrorist Agents
B.anthracis, the bacterium that causes anthrax.
Yersini pestis, the bacterium that causes plague.
Variola virus, the virus that causes smallpox.
Botulinum toxin, a protein toxin produced by
Clostridium botulinum, the bacterium that causes
botulism.
The following table is a list of the most likely candidates for biowarfare and/or
bioterrorism for human diseases:
Disease
Symptoms
Treatment
Anthrax
(bacterium)
High Fever, labored breathing
antibiotic, tachycardia
vaccine
Small Pox Fever
(virus)
Headache, vomiting
vaccine, bleeding
cidofovir
Aflatoxin (fungal
toxin)
Nausea, vomiting, then acute liver failure
or cancer (long term)
Botulism (bacteria Nausea, fatigue, cramps, headache,
toxin)
respiratory paralysis
equine antitoxin
Plague
(bacterium)
antibiotic, vaccine
lung infection, pneumonia
Bacillus anthracis
•Aerobic, spore forming, Grampositive capsulated rod
•The spore has a capacity to survive
in the environment for decades
•It is a relative of B cereus/thuringensis
•Pathogenicity depends on two plasmids, pX01 & pX02
Bacillus anthracis- the cause of anthrax
 B. anthracis is a gram-positive spore-forming rod. Spores are the
infective forms for humans and other animal.
 Anthrax can enter the human body through the intestines (ingestion),
lungs (inhalation), or skin (cutaneous) and causes distinct clinical
symptoms based on its site of entry.
 The second form of anthrax, the most lethal form, is inhalation
anthrax.
 Spores inhaled into the lungs goes to the lymph nodes of the chest.
 In the lungs and in the lymph nodes, the spores germinate into actively
dividing bacteria, which begin to produce lethal toxin.
 Anthrax is usually contracted by handling infected animals or their
wool.
Small pox
 Smallpox is a devastating and disfiguring disease that is
highly infectious.
 It is caused by Variola virus (also known as smallpox virus).
 Smallpox in aerosol form can survive for at least 24 hours.
 The smallpox virus is highly infectious at low doses.
 The smallpox patients would be extremely ill with aching
pains and fever and would be hospitalized.
Smallpox (Variola virus)
Botulin
 Clostridium botulinum produces botulin, a nerve toxin,
causes serious paralytic illness.
 Botulinic toxin is a powerful known toxins: about one
microgram is lethal to humans.
 It blocks nerve function and leads to respiratory and
musculoskeletal paralysis.
Ebola
 Ebola hemorrhagic fever is caused by several Ebola
viruses.
 Ebola viruses are members of the filovirus family.
 People infected with Ebola virus have sudden fever,
weakness, muscle pain and diarrhea, to name a few.
 Death rates range from 50% to 90%.