Study Notes on Microbes in Human Welfare

Study Notes on Microbes in Human Welfare


  • Microbes are the major components of biological systems on this earth.
  • Microbes are present everywhere, in soil, water, air, inside our bodies and that of other animals and plants.
  • They are present even at sites where no other life-form could possibly exist
  • Microbes are diverse: protozoa, bacteria, fungi and microscopic plants viruses, viroids and also prions that are proteinaceous infectious agents.
  • They also cause diseases in animals and plants.
  • Several microbes are useful to man in diverse ways.

 

MICROBES IN HOUSEHOLD PRODUCTION

  • Micro-organisms such as Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it to curd.

Study Notes on Microbes in Human Welfare

  • The LAB produces acids that coagulate and partially digest the milk proteins.
  • Improves nutritional quality of milk by increasing vitamin B12.
  • The LAB plays a very beneficial role in checking disease-causing microbes.
  • The dough, which is used for making bread, is fermented using baker’s yeast (Saccharomyces cerevisiae).

Study Notes on Microbes in Human Welfare

  • A number of traditional drinks and foods are also made by fermentation by the microbes.
  • Microbes are also used to ferment fish, soybean and bamboo shoots to make foods.
  • Microbes also used to make cheese.
  • The large holes in ‘Swiss cheese’ are due to production of a large amount of CO2 by a bacterium named Propionibacterium sharmanii.

Study Notes on Microbes in Human Welfare Study Notes on Microbes in Human Welfare

  • The ‘Roquefort cheese’ are ripened by growing a specific fungi on them, which gives them a particular flavour.

Study Notes on Microbes in Human Welfare

MICROBES IN INDUSTRIAL PRODUCTS

  • Beverages and antibiotics are synthesised by using microbes.
  • Production on an industrial scale requires growing microbes in very large vessels called fermentors FERMENTED BEVERAGES :
  • Microbes especially yeasts have been used for the production of beverages like wine, beer, whisky, brandy or rum.
  • Saccharomyces cerevisiae is used for fermenting malted cereals and fruit juices, to produce ethanol.
  • Depending on the type of raw material used for fermentation and the type of processing different types of alcoholic drinks are obtained.
  • Wine and beer are produced without distillation whereas whisky, brandy and rum are produced by distillation of the fermented broth.

Study Notes on Microbes in Human Welfare

ANTIBIOTICS :

  • Antibiotics are chemical substances, which are produced by some microbes and can kill or retard the growth of other (disease-causing) microbes.
  • Penicillin was the first antibiotic to be discovered.

Study Notes on Microbes in Human Welfare

  • Alexander Fleming while working on Staphylococci bacteria, once observed a mould growing in one of his unwashed culture plates.

Study Notes on Microbes in Human Welfare

  • Around it, Staphylococci could not grow.
  • It was due to a chemical produced by the mould and he named it Penicillin after the mould Penicillium notatum.
  • Its full potential as an effective antibiotic was established much later by Ernest Chain and Howard Florey.
  • Fleming, Chain and Florey were awarded the Nobel Prize in 1945, for this discovery.
  • Antibiotics have greatly improved our capacity to treat deadly diseases such as plague, whooping cough (kali khansi), diphtheria (gal ghotu) and leprosy (kusht rog).

CHEMICAL, ENZYMES AND OTHER BIOACTIVE MOLECULES :

  • Microbes are also used for commercial and industrial production of certain chemicals like organic acids, alcohols and enzymes.
  • Examples of acid producers are Aspergillus niger (a fungus) of citric acid, Acetobacter aceti (a bacterium) of acetic acid; Clostridium butylicum (a bacterium) of butyric acid and Lactobacillus (a bacterium) of lactic acid.
  • Microbes are also used for the production of enzymes.
  • Lipases are used in detergent formulations and are helpful in removing oily stains from the laundry.
  • Streptokinase produced by the bacterium Streptococcus and modified by genetic engineering is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infraction leading to a heart attack.
  • Cyclosporin A, that is used as an immunosuppressive agent in organ-transplant patients, is produced by the fungus Trichoderma polysporum.
  • Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents.
  • It acts by competitively inhibiting the enzyme responsible for the synthesis of cholesterol.

MICROBES IN SEWAGE TREATMENT

  • Municipal waste-water is also called sewage.
  • It contains large amounts of organic matter and microbes.
  • Many of which are pathogenic.
  • Sewage is treated in sewage treatment plants (STPs) to make it less polluting.
  • Treatment of wastewater is done by the heterotrophic microbes naturally present in the sewage.
  • Primary treatment: These treatment steps basically involve physical removal of particles, large and small from the sewage through filtration and sedimentation.
  • Initially, floating debris is removed by sequential filtration.
  • Then the grit (soil and small pebbles) are removed by
  • Solids that settle, form the primary sludge and the supernatant forms the effluent.
  • The effluent from the primary settling tank is taken for secondary treatment.
  • Secondary treatment is also called Biological treatment.
  • The primary effluent is passed into large aeration tanks
  • where it is constantly agitated mechanically and the air is pumped into it.
  • This allows vigorous growth of useful aerobic microbes into
  • Flocs are masses of bacteria associated with fungal filaments to form mesh-like structures).
  • These microbes consume the major part of the organic matter in the effluent.
  • This significantly reduces the BOD (biochemical oxygen demand) of the effluent.
  • The sewage water is treated until the BOD is reduced.
  • The greater the BOD of wastewater more is its polluting potential.
  • The effluent is then passed into a settling tank where the bacterial ‘flocs’ are allowed to sediment.
  • This sediment is called activated sludge.
  • A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum.
  • The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters.
  • Other kinds of bacteria, which grow anaerobically, digest the bacteria and the fungi in the sludge.
  • During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide.
  • The effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.
  • The Ministry of Environment and Forests has initiated the Ganga Action Plan and Yamuna Action Plan to save the major rivers of our country from pollution.

Study Notes on Microbes in Human Welfare

MICROBES IN PRODUCTION OF BIOGAS

  • Biogas is a mixture of gases (containing predominantly methane) produced by the microbial activity
  • May be used as fuel.
  • The type of gas produced depends upon the microbes and the organic substrates they utilise. Bacteria, which grow anaerobically on cellulosic material, produce a large amount of methane along with CO2 and H2.
  • These bacteria are collectively called methanogens, an example is Methanobacterium.
  • These bacteria are commonly found in the anaerobic sludge during sewage treatment.
  • These bacteria are also present in the rumen (a part of the stomach) of cattle.
  • A lot of cellulosic material present in the food of cattle
  • In the rumen, these bacteria help in the breakdown of cellulose
  • Thus, the excreta (dung) of cattle is rich in these bacteria. Dung can be used for the generation of biogas, commonly called gobar gas.
  • The biogas plant consists of a concrete tank (10-15 feet deep).
  • Bio-wastes are collected and a slurry of dung is fed in it. A floating cover is placed over the slurry, which keeps on rising as the gas is produced in the tank
  • Due to the microbial activity.
  • The biogas plant is connected to a pipe to supply biogas to nearby houses.
  • The spent slurry is removed through another outlet and may be used as fertiliser.
  • The biogas produced is used for cooking and lighting.
  • The technology of biogas production was developed in India mainly due to the efforts of the Indian Agricultural Research Institute (IARI) and Khadi and Village Industries Commission (KVIC).

Study Notes on Microbes in Human Welfare

 

MICROBES AS BIOCONTROL AGENTS

  • Biocontrol refers to the use of biological methods for controlling plant diseases and pests. the use of biocontrol measures will greatly reduce our dependence on toxic chemicals and pesticides.
  • An example of microbial biocontrol agents is the bacteria Bacillus thuringiensis (often written as Bt).
  • It is introduced in order to control butterfly caterpillars.
  • These are available in sachets as dried spores which are mixed with water and sprayed onto vulnerable plants such as brassicas and fruit trees, where these are eaten by the insect larvae.
  • In the gut of the larvae, the toxin is released and the larvae get killed.
  • The bacterial disease will kill the caterpillars, but leave other insects unharmed.
  • Scientists have introduced thuringiensis toxin genes into plants.
  • Such plants are resistant to attack by insect pests.
  • A biological control developed for use in the treatment of plant disease is the fungus Trichoderma

Study Notes on Microbes in Human Welfare

  • They are free-living fungi that are very common in the root ecosystems.
  • They are effective biocontrol agents of several plant pathogens.
  • Baculoviruses are pathogens that attack insects and other arthropods.
  • The majority of baculoviruses used as biological control agents are in the genus
  • These viruses are excellent for species-specific, narrow spectrum insecticidal applications.
  • This is especially desirable when beneficial insects are being conserved to aid in overall integrated pest management (IPM) programme, or when an ecologically sensitive area is being treated.

Study Notes on Microbes in Human Welfare

MICROBES AS BIOFERTILISERS

  • Bio fertilisers are organisms that enrich the nutrient quality of the soil.
  • The main sources of bio fertilisers are bacteria, fungi and cyanobacteria.
  • The bacteria Rhizobium fix atmospheric nitrogen into organic forms, which is used by the plant as nutrient.

Study Notes on Microbes in Human Welfare

  • Other bacteria can fix atmospheric nitrogen while free-living in the soil (examples Azospirillum and Azotobacter)
  • They enrich the nitrogen content of the soil.
  • Fungi also form symbiotic associations with plants (mycorrhiza).
  • Many members of the genus Glomus form mycorrhiza.
  • The fungal symbiont in these associations absorbs phosphorus from soil and passes it to the plant.

Study Notes on Microbes in Human Welfare

  • Plants having such associations show other benefits also, such as resistance to root-borne pathogens, tolerance to salinity and drought, and an overall increase in plant growth and development.
  • Cyanobacteria are autotrophic microbes widely distributed in aquatic and terrestrial environments e.g. Anabaena, Nostoc, Oscillatoria

Study Notes on Microbes in Human Welfare

  • In paddy fields, cyanobacteria serve as an important biofertiliser.
  • Blue-green algae also add organic matter to the soil and increase its fertility.
  • Bio fertilisers replenish soil nutrients and reduce dependence on chemical fertilisers.

REFERENCES

  1. https://ncert.nic.in/ncerts/l/lebo110.pdf