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• Lactic acid bacteria (LAB) convert milk into curd, improving nutritional quality and preventing disease. • • LAB also play a role in checking disease-causing microbes in the stomach. • • Dough, used in food production like dosa and idli, is fermented by bacteria, producing CO2 gas. • • Baker’s yeast is used for bread fermentation. • • Microbes also ferment traditional drinks and foods like 'Toddy', fish, soyabean, and bamboo shoots. • • Cheese, one of the oldest food items, is a product of microbes, with unique texture, flavor, and taste.
• 'Swiss cheese' has large holes due to CO2 production by Propionibacterium sharmanii, while 'Roquefort cheese' is ripened by specific fungi.
Fermented Beverages • • Microbes, particularly yeasts, have been used for the production of beverages like wine, beer, whisky, brandy, or rum. • • The yeast Saccharomyces cerevisiae, used for bread-making, is used for fermenting malted cereals and fruit juices to produce ethanol. • • Different types of alcoholic drinks are obtained based on the type of raw material used for fermentation and the type of processing (with or without distillation). Antibiotics • • Antibiotics produced by microbes are significant discoveries of the 20th century.
• Antibiotics are chemical substances produced by some microbes and can kill or retard the growth of other disease-causing microbes. • • Penicillin, the first antibiotic, was discovered by Alexander Fleming and later established by Ernest Chain and Howard Florey. • • Other antibiotics were also purified from other microbes, improving our capacity to treat deadly diseases such as plague, whooping cough, diphtheria, and leprosy. Chemicals, Enzymes and other Bioactive Molecules • • Microbes are used for the production of organic acids, alcohols, and enzymes.
• Acid producers include Aspergillus niger, Acetobacter aceti, Clostridium butylicum, and Lactobacillus. • • Microbes also produce enzymes, such as lipases used in detergent formulations and streptokinase used as a 'clot buster'. • • Cyclosporin A, produced by the fungus Trichoderma polysporum, is used as an immunosuppressive agent in organ-transplant patients. • • Statins produced by the yeast Monascus purpureus have been commercialised as blood-cholesterol lowering agents.
• Wastewater, also known as sewage, is generated daily in cities and towns, containing 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 involves two stages: primary treatment and secondary treatment. • • Primary treatment involves physical removal of particles through filtration and sedimentation, forming the primary sludge and the effluent. • • Secondary treatment involves the growth of aerobic microbes into flocs, which consume the organic matter in the effluent, reducing the biochemical oxygen demand (BOD).
• The BOD test measures the rate of oxygen uptake by micro-organisms in a sample of water, indirectly indicating the organic matter present in the water. • • Once the BOD of sewage is reduced, the effluent is passed into a settling tank where the bacterial 'flocs' sediment, called activated sludge. • • The remaining part of the sludge is pumped into anaerobic sludge digesters, where bacteria digest the bacteria and fungi in the sludge, producing 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 major rivers from pollution.
• Biogas is a mixture of gases produced by microbial activity, primarily methane, used as fuel. • • The type of gas produced depends on the microbes and the organic substrates they use. • • Methanogens, bacteria that grow anaerobically on cellulosic material, produce a large amount of methane along with CO2 and H2. • • Methanobacterium, a common bacterium, is found in anaerobic sludge during sewage treatment and in cattle's rumen. • • These bacteria aid in breaking down cellulose in cattle's food, contributing to the nutrition of cattle. • • The excreta (dung) of cattle, known as gobar, is rich in these bacteria, which can be used for biogas generation.
• Biogas plants consist of a concrete tank, a slurry of dung, and an outlet connected to a pipe for supply to nearby houses. • • Biogas produced is used for cooking and lighting in rural areas. • • The technology of biogas production was developed in India mainly through the efforts of the Indian Agricultural Research Institute (IARI) and the Khadi and Village Industries Commission (KVIC).
• Biocontrol refers to the use of biological methods to control plant diseases and pests. • • Chemicals like insecticides and pesticides are toxic and harmful to humans and animals, polluting the environment. • • Organic farming focuses on natural predation rather than chemical methods to control pests. • • Organic farming aims to maintain biodiversity and sustainability by creating a system where pests are managed within a vibrant ecosystem. • • The eradication of pests is seen as undesirable as it affects beneficial predatory and parasitic insects. • • Biocontrol measures reduce dependence on toxic chemicals and pesticides.
• Understanding the life forms, predators, and pests in the field is crucial for developing appropriate biocontrol methods. • • Beetles like Ladybird and Dragonflies are useful for controlling aphids and mosquitoes. • • Bacillus thuringiensis (Bt) is a microbial biocontrol agent for controlling butterfly caterpillars. • • Trichoderma species are effective biocontrol agents of several plant pathogens. • • Baculoviruses, particularly in the genus Nucleopolyhedrovirus, are ideal for species-specific, narrow spectrum insecticidal applications. • • These viruses have shown no negative impacts on plants, mammals, birds, fish, or non-target insects.
• Overuse of chemical fertilisers has led to environmental pollution. • • Overuse of chemical fertilisers has led to pressure to switch to organic farming. • • Biofertilisers are organisms that enrich soil nutrient quality. • • Bacteria, fungi, and cyanobacteria are main sources of biofertilisers. • • Bacteria like Rhizobium and Azospirillum fix atmospheric nitrogen, enriching soil nitrogen content. • • Fungi form symbiotic associations with plants, absorbing phosphorus and passing it to the plant. • • Plants with such associations show benefits like resistance to pathogens, tolerance to salinity and drought, and increased growth.
• Cyanobacteria, like Anabaena, Nostoc, and Oscillatoria, serve as important biofertilizers in paddy fields. • • Blue green algae also add organic matter to soil and increase fertility. • • Commercially available biofertilisers are used by farmers to replenish soil nutrients and reduce reliance on chemical fertilisers.
• Microbes are essential to life on earth, not all are pathogenic. • • They are used in daily life, including in milk, bread, cheese, and industrial products. • • Lactic acid bacteria (LAB) convert milk into curd, while Saccharomyces cerevisiae ferments bread dough. • • Microbes also impart texture, taste, and flavor to cheese. • • Antibiotics produced by microbes are used to control infectious diseases like diphtheria, whooping cough, and pneumonia. • • Microbes treat sewage through activated • sludge formation, aiding in water recycling. • • Methanogens produce biogas, used as energy in rural areas. • • Biocontrol measures help avoid heavy use of toxic pesticides.
• The need for biofertilizers over chemical fertilisers is increasing.
