Economical importance of bacteria - benificial aspects of bacteria and harmful aspects of bacteria , fungi- mycorrhiza, yeast Cakes , edible fungi , industrial uses..

1. Economic importance of
bacteria and fungi
By
sneha sahu
Sant gahira guru University ambikapur chhattisgarh

2. Economic importance of bacteria
A. Benificial aspects of bacteria.
1. Role of bacteria in soil fertility
•Nitrogen is an essential constituent of many biologically significant
organic molecules like proteins, nucleic acids, vitamins, coenzymes,
alkaloids etc.
•Certain bacteria play an important role Nitrogen fixation,
ammonification , nitrification and thus help to increase the fertility of
the soil.
Nitrogen fixing bacteria
• Although 79% of the atmosphere is Nitrogen, it can not be used directly
by plants. Plants can absorb Nitrogen only in Nitrogen fixing bacteria can
fix the free nitrogen of the atmosphere into absorbable form of the form
of nitrates. nitrates.
•Nitrogen fixing bacteria are of two types viz. symbiotic nitrogen fixers
and free living (asymbiotic ) nitrogen fixers.

3. Conti…
Symbiotic nitrogen fixing bacteria
•Establish symbiotic relationship with leguminous plants and fix free
Nitrogen of the atmosphere into absorbable form of nitrates and increase
the fertility of the soil.
•These are rod shaped, gram negative, motile bacteria that can grow in
symbiotic association with leguminous plants and both the partners are
mutually benefitted.
•The bacteria receive nutrients from the plants and the plant in turn get
nitrogenous compounds.
•Infection of the roots of a leguminous plant with suitable species of
these bacteria leads to the formation of root nodules.
•e.g. Bacteria like Rhizobium leguminosarum, Bradyrhizobium
japonicum, Sinorhizobium meliloti etc

4. Conti…
Free- living, aerobic nitrogen fixing bacteria
• Live independently in the soil and fix free Nitrogen of the atmosphere
into absorbable forms.
•These bacteria are the chief suppliers of Nitrogen in grass lands and
other similar ecosystems that lack plants with nitrogen fixing symbionts.
•e.g. Azotobacter vinelandii, Azospirillum lipoferum etc.
Nitrogen fixation by Cyanobacteria
Cyanobacteria like Nostoc punctiforme, Anabaena azollae etc. can also
fix free nitrogen of the atmosphere by means of heterocysts and thus
increase fertility of the soil.
Ammonification
•Ammonificationcteria like Bacillus subtilis, Bacillus macerans, Proteus
terrae , Pseudomonas fluorescens etc.
•degrade dead organic matter of plants and animals into simple
compounds like ammonia enhance the fertility of the soil

5. Conti…
Nitrification
Nitrifying bacteria like Nitrosomonas (Nitrosomonas europaea),
Nitrosococcus (Nitrosococcus oceani) oxidise ammonia to nitritesand
Nitrobacter species etc. (e.g. Nitrobacter vulgaris) oxidise nitrites to
nitrates and increase the fertility of the soil.
Nitrogen fixation by Filamentous bacteria (Actinomycetes )
Form nodules in the roots of non -leguminous plants like Casuarina. e.g.
Frankia
Phosphorous solubilizers or Phosphobacteria
Solubilize different forms of insoluble phosphates by producing citric
acid, succinic acid, fumaric acid etc.
e.g. Bacillus polymyxa B. megatherium var. phosphaticum Pseudomonas
striata

6. Conti…
Bacteria as Biofertilizers
• Cultures of improved strains of beneficial bacteria which when applied to the
seed or soil, colonize the rhizosphere or the interior of the plants and stimulate
plant growth by increasing the availability of nutrients.
• Improve cycling of nutrients and increase soil fertility.
• Increase porosity and water holding capacity of the soil and provide pro
tection against drought. Enhance seed germination.
• Increase crop yield to 20 - 30 % Cheap, convenient and ecofriendly.
•Application of biofertilizers have considerable importance in sustainable
agriculture.
Bacteria as decomposers - Nature's scavengers
• Saprophytic bacteria bring about the decomposition of dead remains of plants
and animals and thus help in sanitation.
•During this process, the bacteria break down the complex organic molecules
into simpler ones and make it available to plants.
• In this way, they help in cycling of nutrients (Biogeochemical cycles) and
improve the fertility of soil.

7. 2. Bacteria in production of antibiotics.
e.g. Antibiotic Bacitracin and Polymixin are produced from Bacillus sps.
Antibiotics Streptomycin, Tetracycline, Erythromycin, Rifamycin etc. are
produced from from Streptyces species. (Actinomycetes or Filamentous
bacteria).
3. Production of Butanol and Propionic acid.
Industrial production of Butanol by fermentation using the bacterium
Clostridium acetobutylicum.
• Industrial production of Propionic acid by fermentation by
Propionibacterium species.
4. Bacteria for the production of medically useful enzyme.
The enzyme Streptokinase - a thrombolytic enzyme used to dissolve
blood clots - produced by several Streptococci mutans, S. feacalis, S.
uberis etc. ) bacteria (e.g. Streptococcus

8. 5. Bacterium as a biocontrol agent
the bacterium bacillus thuringiensis can be used as a biocontrol agent.
6. Agrobacterium mediated gene transfer technique.
The soil bacterium, Agrobacterium tumefuciens , known as natural plant genetic
engineer, is used to produce many genetically modified plants.
7. production of biogas.
Several bacteria are involued in the production of biogas from crowding , animal
wastes , other biodegradable wastes etc.
8. Retting of fibers.
Bacteria are involved in the retting of fibers of coconut jute , flax , hemp etc.
9. leather industry
in leather industry removal of hairs , fats and other tissues from raw hide is done
by bacteria.
10. Biodegradable plastics .
Poly beta-hydroxybutyrate , type Of reserve food in certain . Bacteria is used for
the production of Biodegradable plastic.

9. B. Harmful aspects of bacteria
1. Reduction in soil fertility by denitrifying bacteria.
Denitrifying bacteria like thiobacillus denitrifications , micrococcus
denitrifycans etc. Convert the nitrites of the soil into free nitrogen of the
atmosphere and thus reduce the fersility of the soil.
2. Bacterial diseases
parasitic bacteria are pathogens and cause various diseases in plants and
animals including man. Eg- bright disease of paddy caused by
xanthonmonas aruyzyae.
Caused by xanthonmonas axonopodis.
3. Bacteria causes food spoilage
food spoilage is the undesirable change in the food. Spoilage causes
changes in the appearance of food, formation of unpleasant teste.
A large number of bacteria cause spoilage of vegetable and fruits-
staphylococcus, streptococcus, bacillus etc.

10. Bacteria causes food poisoning
Botulism
An anarobic bacterium, clostridium botelinium produces a neurotoxin botuling
which produces food poisoning called botlism.
Salmonellosis
Caused by salmonella bacteria commonlly associated with egg meat and Poultry.

11. Economic importance of fungi
Uses as decomposers of wastes
• Many saprophytic fungi decompose plant and animal debris and continuously remove
it from the man’s environment.
• During this process they also liberate a large amount of CO2, which is used by the
green plants for the synthesis of food by photosynthesis.
• Decomposition of organic wastes also result in the formation of humus, which is
needed for the growth of plants.
Mycorrhiza
•A symbiotic association of fungi and the roots of higher plants is called mycorrhiza.
Literal meaning of mycorrhiza is fungus root.
•There are mainly two kinds of mycorrhizae- ecto & the endo mycorrhizae.
• in case of ectomycorrhizae, the fungus completely encloses the rootlets in a sheath.
The hyphhae penetrate only between the cells of root cortex( intercellular).
• In case of endomycorrhizae, the fungus does not form an externalsheath but lives
within the cells of the root(intracellular). Mycorrhizal roots generally lack root hairs.
•This association helps in the absorption of nutrients.
• The mycorrhizal roots are generally resistant to infection.

12. Edible fungi
➢ There are about 200 species of fungi which are used as food.
➢ The most important among them are common field mushroom (Agaricus
compestris), puff balls (Lycoprdon & Clavatia), morels or guchi (Morchella
esculenta), Catherella cibarius & Boletus edulis is very high & almost equal to
animal protein.
➢ Though the food content is not high in these edible fungi, they are rich source
of vitamins. They are delicious in taste and regarded as delicacies of the
table.
➢ The common mushrooms Agaricus compestris is cultivated on commercial
basis in Kashmir, Himachal Pradesh, South India & other states of India. These
are usually grown on compost beds in mushroom houses.
➢ Some of the mushrooms are poisonous (Amantia muscaris, Boletus satanas,
Entoloma lividium & Russula spp).
➢ They are fatal & cause death if consumed, therefore, they are popularly
called "death cups" or "destroying angels".
➢ The edible species are commonly called mushrooms whereas poisonous ones
are called toadstools.

13. Yeast Cakes
• The large scale production of yeast cake is called 'microbial farming’
• These are prepared by mixing a large number of yeast cells with some inert
substances such as, starch and then compressed to form cakes.
• Yeast cells are rich in protein and hence, the yeast cakes are eaten directly as
health giving food.
• Yeast cakes are extensively used in baking and brewing industries.
• They are also used in laboratories to demonstrate fermentation in sugary
solution.
Uses in medicine
•Many strains of fungi produce potential metabolities which are used as
medicines or in the preperation of medicines.
• Some metbolic products used in medicine are- Ergot: It is a most useful drug
obtained from sclerotia of Claviceps purpure. The fungus is parasitic on grasses,
especially rye. The disease is called 'ergot of rye’.
• The ergot contains alkaloid- ergotinine & many other substances like- ergotonic
acid, cornutine, spacelotoxin, etc.
• The drug stimulate muscles of uterus & used as abortitacient to assit child
birth.

14. • It is also used to increase blood pressure, controls uterine haemorrhage & in many
other uterine disturbances.
• Antibiotics: An organic substance; produced by a microorganism, which inhibit or
reduce the growth of certain microorganism is called an antibiotic.
Vitamins
• Fungi are rich source of many vitamins.
• Vitamins B complex is obtained from yeasts. Other vitamins obtained from ye
asts & moulds are - vitamin D, Riboflavin, Ergosterol, etc.
Industrial uses
• Fungi are used in many important industries in the production of varied products.
Alcoholic fermentation: The common alcoholic beverages- wine & beer are
fermentation products by the activity of different species of Saccharomyces.
•Wine is made from juice of grapes or other fruits by allowing yeast (Saccharomyces
cerevisiae) to induce alcoholic fermentation. It contains 10-12 % alcohol.
• Beer is chiefly made from barley grains. The starch of grain is first converted to
fermentablesugars, maltose & glucose by the process called malting.
• It is then fermented by special strains of Saccharomyces cerevisiae. The beer
contains 3 - 8 % alcohol.
• Other brands such as, whisky, brandy, rum, and gin are distilled alcoholic beverages.
Whisky is distilled from fermentedmash of cereals or potatoes & contains upto 50%
alcohol.
• Brandy is distilled from wine & contains upto 60 - 70 % alcohol. » Rum is obtained by
distillation of fermented sugarcane jauice or molasses & contains about 40% alcohol.

15. Enzymes
• A large no of enzymes such as, protease, invertase, maltase, catalase,
cellulase, amylase, pectinase, & glucose oxidase are produced by fungi. Maltase
& x amylase are obtained from Mucor rouxii, Rhizopus japonicus & aspergillus
niger.
• Glucose oxidase is obtained from Penicillium chrysogenum.
• Pectinase, protease & catalase are obtained from Aspergillus niger, » Invertase
is obtained from yeast.
Gibberellic acid
•. The phytoharmone gibberellic acid is obtained from the culture of Gibberella
fujikuroi & Fusarium moniliforme.
• It is used to induce growth and flowering in plants.
Biological Control
•Many soil inhabitant fungi parasites over soil born pathogen and thus control
plant diseases.
• Trichoderma lignorum & Gliocladium fimbriayum, found in damp soil, inhibit
the growth of Pythium sp. & control damping off disease.