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Unit-VI, Chapter 14 Microbes in Human Welfare

         If we agree that God is omnipresent and omnipotent we should assign the word "God" to the little microorganisms which are seldom seen with naked eye but are truly omnipresent and omnipotent. It is never an exaggeration to say that the world is burial ground of litter and dead bodies without the existence of microorganisms. Microorganisms exist everywhere, in water, air and soil. They are present on living and nonliving matter. Some can survive temperatures as high as 140º while other can live even at less than 0º temperatures. They cause decomposition, fermentation, chemical conversion and keep the nutrient cycles in place. Without the role of microorganisms we cannot enjoy a meal with curd and a drink with wine. We cannot think of idly or dosa without these little creatures. Many medicines, antibiotics, alcohols, vaccines and other industrial products are the result of microbes and their metabolism. We cannot even imagine agriculture without microbes. In fact it is the microorganisms that do agriculture not man.

       That is why the great scientist Anton Von Leuwenhoek exclaimed "Dear God, What marvels there are in so small a creature". Very less percentage of microbes is harmful and pathogenic. Some of them cause diseases to humans, plants and animals. However microbes are indispensible tools of human welfare today.
       In this chapter we will discuss about the importance of microbes in human welfare with few examples.
Microbes in household products:
* Using friendly bacteria for betterment of human health led to the concept of probiotics. One such bacterium is LAB.
* Lactobacillus and Lactic Acid Bacteria (LAB) grow in milk and convert it to curds.
* They produce acids which coagulate and partly digest milk protein. Thus curd and buttermilk are easily digestible when compared to milk.
* They also increase vitamin B12 content thus improving the nutritional quality.
* They check disease causing microbes in the stomach.
* Some bacteria help in fermentation and produce CO2 which causes rising of dough during preparation of bread, idly or dosa.

* Saccharomyces cervisiae (baker’s yeast or brewer’s yeast) is used for making bread as well as fermenting malted cereals and fruit juices to produce alcohols.
* Similarly "Toddy" is made by fermenting sap of palms with bacteria.
* Bacteria are used to ferment fish, soyabean and bamboo shoots to improve the food quality.
* The texture, flavour and taste of cheese depend on the kind of bacteria used for fermenting it.
* Propionibacterium sharmanii is used to produce large amounts of CO2 which produces large holes in "Swiss Cheese".
* Similarly Roquefort cheese is ripened by using a fungus which gives it a characteristic flavour.
Microbes in Industrial Products
Fermented beverages:

* Saccharomyces cervisiae is used to ferment malted cereals and fruit juices to produce ethanol.
* Large vessels called fermenters are used to produce alcohols or fermented beverages.
* Wine and Beer are produced without distillation.
* Whisky, brandy and rum are produced by distillation of fermented broth.

Antibiotics:
* In view of human health antibiotics are pro-life which save life by fighting disease causing microorganisms.
* Alexander Fleming observed that the fungus Pencillium notatum restricted the growth of Staphylococci bacteria.
* Later Ernest Chain and Howard Florey established that penicillin obtained from Pencillium notatum was an effective antibiotic.
* Several diseases like plague, whooping cough, diphtheria and leprosy are cured today with the help of antibiotics.
Chemicals, Enzymes and other Bio active molecules:
* Microbes are used to produce organic acids, alcohols and enzymes for industrial use.
* Acid producers
   Aspergillus niger – Citric acid
   Acetobacter aceti – Acetic acid
   Clostridium butylicum – Butyric acid
   Lactobacillus – Lactic acid

* Yeast (Saccharomyces cervisiae) is used to produce ethanol.
* Microbes which produce the enzyme lipase are used to remove oily stains on clothes.
* Some microorganisms produce pectinases and proteases to clarity fruit juices.
* Streptococcus produces streptokinase which is used as ‘clot buster’ for removing clots from blood vessels of heart patients.
* The fungus Trichoderma polysporum produces an immunosuppressive agent called cyclosporin A which is used during organ transplantation.
* The yeast Monascus purpureus produces Statins which lower blood cholesterol by inhibiting the enzyme responsible for the synthesis of cholesterol.
Microbes in Sewage Treatment
* Municipal waste water which contains large amount of organic matter and many pathogenic microbes is referred to as "Sewage".
* If this sewage is disposed into water or soil without treatment the water and soil get polluted with many pathogens.
* That is the reason why the sewage is treated in sewage treatment plants (STP) before being disposed to reduce the pollution.

Sewage treatment involves two steps:
          Primary treatment
          Secondary treatment
* Primary treatment involves physical removal of large and small particles by filtration and sedimentation.
* Floating debris is removed by sequential filtration.
* The grit is removed by sedimentation leaving the primary sludge at the bottom.
* The effluent is taken for secondary treatment.
* The secondary treatment involves:
          Aeration by mechanical agitation
          Anaerobic digestion of the activated sludge
* The primary effluent is agitated mechanically in aeration tanks and air is pumped to allow the growth of aerobic microbes.
* Flocs of bacteria and fungi are formed which consume the organic matter and reduce Biochemical Oxygen Demand.

* The BOD (Biochemical Oxygen Demand) is a measure of uptake of oxygen by microorganisms in a sample of water. It is the amount of oxygen that would be consumed if all the organic matter in one litre of water were oxidised by bacteria.
* High BOD indicates high rate of pollution.
* The activated sludge is pumped into anaerobic sludge digester where anaerobic bacteria digest the bacteria and fungi present in the sludge.
* During this process a mixture of methane, hydrogen sulphite and CO2 are released which form biogas.
* After secondary treatment the sewage is released into natural water bodies like rivers and streams.
Microbes in production of biogas
* Biogas is a mixture of gases like methane and butane produced by microbial activity which may be used as fuel.
* Anaerobic methanogens like Methano coccus and Methano Bacillus help in biogas production .
* These bacteria produce large amount of methane and butane.

* The same bacteria are present in the stomach of ruminates like cows and buffaloes which help in digestion of cellulose.
* The biogas plant contains a concrete tank, a floating cover and an outlet connected to a gas pipe.
* The cow dung slurry after production of biogas can be used as rich organic manure.
* Indian Agricultural Research Institute and Khadi and Village Industries Commission developed the technology of biogas production in India.
Microbes as Bio control Agents
      Bacteria, fungi and viruses are used as bio control agents in agriculture. Bacteria like Bacillus thuringiensis are used to control butterfly caterpillars which feed on leaves of crop plants. The bacteria are available as dried spores which are mixed with water and sprayed on the affected crop. The bacteria destroy only caterpillars by producing toxins in the gut of the larva. But these bacteria do not harm other useful insects. Hence Bacillus thuringiensis genes are used in genetic engineering to produce genetically modified crops like Bt cotton and Bt brinjal.
      Trichoderma viridi is a free living fungus which inhabits the rhizosphere. It has antagonistic properties against disease causing bacteria and fungi. Thus it protects the roots from infection of pathogens. Hence it is used as a bio control agent.

      Baculo viruses like NPV (Nuclear Polyhedrosis Virus) and CPV (Cytoplasmic Polyhedrosis Virus) act against arthropods insects and hence used to control them. They are species specific and have no negative impact on plants, mammals, birds etc., Hence NPVs are variously used in integrated pest management programmes.
Microbes as Biofertilizers:
      Organic farming is a self-sustainable agricultural practice which employs local inputs, natural manures made from plant and animal wastes, natural pesticides from plant extracts and microorganisms to enrich the soil. It aims at producing crops by conserving soil, water and atmospheric thus reducing pollution and ecological damage. Today it is known by various names like natural farming, zero budget farming and spiritual farming. It is a holistic approach which conserves the food chains and food webs. It does not encourage indiscriminate use of chemical fertilizers but promotes use of substances locally available to the farmer. It facilitates checking of pests without complete eradication of them. Organic farming blends traditional knowledge with modern technology and employs vermicomposts, cultures of microorganisms and bio pesticides to produce high yields and healthy yields.

Role of plant microbes in organic farming:
Microorganisms as bio fertilizers:

       Bio fertilizers are organisms that enrich the nutrient quality of the soil. Some of the microorganisms used as bio fertilizers are:
* Bacteria – Rhizobium, Azospirillum, Azotobacter
* Fungi – Glomus
* Cyano bacteria – Anabaena, Nostoc, Oscillatoria
Role of organisms as bio fertilizers:
* Rhizobium fixes atmospheric nitrogen into ammonia by symbiotic association with legume roots which is absorbed by the plant.
* Azospirillum and Azotobacter are free living nitrogen fixing bacteria.
* Glomus forms mycorrhizae in symbiosis with root of higher plants and helps in absorption of phosphorus from the soil.
* It also protects the plants from root borne pathogens, offers tolerance to salinity and drought, helps in increase of plant growth.
* Cyano bacteria not only fix nitrogen but also add organic matter to the soil.

Microbes as pest control agents:
       Bacteria, fungi and viruses are used as bio control agents in agriculture. Bacteria like Bacillus thuringiensis are used to control butterfly caterpillars which feed on leaves of crop plants. The bacteria are available as dried spores which are mixed with water and sprayed on the affected crop. The bacteria destroy only caterpillars by producing toxins in the gut of the larva. But these bacteria do not harm other useful insects. Hence Bacillus thuringiensis genes are used in genetic engineering to produce genetically modified crops like Bt cotton and Bt brinjal. 
       Trichoderma viridi is a free living fungus which inhabits the rhizosphere. It has antagonistic properties against disease causing bacteria and fungi. Thus it protects the roots from infection of pathogens. Hence it is used as a bio control agent.
       Baculo viruses like NPV (Nuclear Polyhedrosis Virus) and CPV (Cytoplasmic Polyhedrosis Virus) act against arthropods insects and hence used to control them. They are species specific and have no negative impact on plants, mammals, birds etc., Hence NPVs are variously used in integrated pest management programmes.

Challenges posed by microbes:
* Mutation of pathogens could produce super microbes which are resistant to drugs.
* They cause emerging and re-emerging infections.
* AIDS, Mad Cow Disease and SARS are some emerging diseases.
* Cholera, Tuberculosis and Dengue are re-emerging diseases.
* Use of biological agents to spread fear and cause death to large populations is called Bioterrorism which is a major threat to the society.

Posted Date : 03-11-2020

గమనిక : ప్రతిభ.ఈనాడు.నెట్‌లో కనిపించే వ్యాపార ప్రకటనలు వివిధ దేశాల్లోని వ్యాపారులు, సంస్థల నుంచి వస్తాయి. మరి కొన్ని ప్రకటనలు పాఠకుల అభిరుచి మేరకు కృత్రిమ మేధస్సు సాంకేతికత సాయంతో ప్రదర్శితమవుతుంటాయి. ఆ ప్రకటనల్లోని ఉత్పత్తులను లేదా సేవలను పాఠకులు స్వయంగా విచారించుకొని, జాగ్రత్తగా పరిశీలించి కొనుక్కోవాలి లేదా వినియోగించుకోవాలి. వాటి నాణ్యత లేదా లోపాలతో ఈనాడు యాజమాన్యానికి ఎలాంటి సంబంధం లేదు. ఈ విషయంలో ఉత్తర ప్రత్యుత్తరాలకు, ఈ-మెయిల్స్ కి, ఇంకా ఇతర రూపాల్లో సమాచార మార్పిడికి తావు లేదు. ఫిర్యాదులు స్వీకరించడం కుదరదు. పాఠకులు గమనించి, సహకరించాలని మనవి.

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