Microbes in Human Welfare

Microbes are tiny living things you cannot see but they help in kitchen every day.

Curd: When you add little old curd to warm milk, bacteria LAB Lactobacillus present in old curd eats lactose milk sugar and makes lactic acid, milk thickens sour curd forms, vitamin B12 increases good for health. At night curd sets because LAB grows faster warm.

Dosa idli batter puffs up because bacteria and yeast produce CO2 gas bubbles, batter becomes fluffy soft, same as bread yeast Saccharomyces cerevisiae baker's yeast makes CO2 bread soft.

Cheese: milk protein + bacteria + enzyme rennin solidifies. Swiss cheese has big holes because bacterium Propionibacterium shermanii makes lots of CO2 gas holes. Roquefort cheese blue fungus gives strong smell.

Toddy is traditional palm sap fermented by yeast little alcohol.

Think microbes are kitchen helpers eating sugar and giving sour, softness, holes, flavour.

In factories microbes grown in big tanks fermenters with sugar, they make useful chemicals.

Alcohol drinks: yeast Saccharomyces cerevisiae converts sugar from grapes barley into ethanol alcohol + CO2 by fermentation. Wine beer made without distillation low alcohol, whisky brandy rum distilled high alcohol.

Antibiotics: first antibiotic penicillin found by Alexander Fleming from fungus Penicillium notatum, it kills bacteria. Penicillin stops bacteria wall making. Many other antibiotics from Streptomyces bacteria like streptomycin tetracycline. Antibiotics kill bacteria not virus.

Organic acids: Aspergillus niger fungus makes citric acid sour lemon taste used cold drinks. Acetobacter aceti makes acetic acid vinegar sour. Clostridium butylicum makes butyric acid smelly butter. Lactobacillus makes lactic acid curd. Enzymes: lipase used in detergent to remove oil stains, pectinase makes fruit juice clear, streptokinase from Streptococcus dissolves blood clots in heart patients clot buster life saving.

Cities make sewage dirty water with waste. Treatment plant uses microbes to clean.

Primary treatment physical big solids removed by filters settling tanks like removing stones.

Secondary biological: water goes to aeration tanks air pumped, bacteria fungus form slimy masses flocs that eat organic waste and reduce BOD Biological Oxygen Demand. BOD is oxygen needed by microbes to eat waste, high BOD means more pollution dirty water, low BOD clean. After eating, flocs settle as activated sludge, some reused as starter. Clean water disinfected released to river.

Sludge from primary and activated sludge sent to anaerobic sludge digesters tanks without oxygen, anaerobic bacteria digest produce biogas methane CH4 50-70% + CO2 + H2S fuel used electricity cooking.

Biogas plant gobar gas plant similar cow dung + water fed into tank, methanogens Methanobacterium anaerobic digest cellulose produce methane inflammable fuel, slurry leftover used as fertilizer rich. Methanogens also in cattle rumen help digest cellulose, in marsh make marsh gas.

So microbes clean water and give fuel both free.

Chemical pesticides kill all insects good and bad and pollute soil water. Better use microbes as biocontrol natural enemies specific.

Bacillus thuringiensis Bt bacteria makes Cry toxin crystal protein that kills caterpillar larvae of cotton bollworm when caterpillar eats it gut alkaline dissolves crystal toxin kills gut lining, safe for humans animals. Bt spray available or gene put into Bt cotton plant makes its own toxin.

Trichoderma fungus lives in roots, attacks other harmful fungi, used for soil borne diseases, biocontrol fungus.

Baculovirus NPV nucleopolyhedrovirus infects caterpillars and other insects and kills them, narrow spectrum only kills specific pest safe for beneficial insects like bees ladybug humans. Used in Integrated Pest Management IPM less pollution no resistance.

So biocontrol uses nature's enemies not chemicals.

Biofertilizers are microbes that give nutrients to plants instead of chemical fertilizer costly polluting.

Rhizobium lives in root nodules of legumes pea bean soybean, converts atmospheric nitrogen N2 to ammonia NH3 by enzyme nitrogenase, plant gives sugar, both benefit symbiosis enriches soil nitrogen.

Azospirillum lives near roots of cereals maize wheat grasses, associative symbiosis fixes N2 and produces auxin growth hormone improves root growth nutrient uptake.

Azotobacter free living bacteria in soil aerobic fixes N2 on its own makes vitamins organic matter good for many crops.

Mycorrhiza Glomus fungus forms association with roots, hyphae thread extend far beyond root increases surface area absorbs phosphorus P from soil insoluble phosphate solubilize transport to plant, plant gives sugar, improves drought tolerance growth.

Cyanobacteria photosynthetic bacteria fix nitrogen blue green algae Anabaena has heterocyst special thick wall cell without oxygen where nitrogenase works because oxygen destroys nitrogenase, Nostoc forms slimy colonies in paddy water soil, Oscillatoria filamentous motile photosynthetic fixes N2 organic matter. In paddy flooded fields cyanobacteria fix N2 naturally reduce urea need, Azolla fern has Anabaena inside leaves biofertilizer for rice.

Full story: kitchen LAB yeast cheese curd bread, factory alcohol antibiotics acids enzymes, sewage BOD ↓ clean water biogas CH4 fuel, biocontrol Bt Trichoderma NPV protects crops, biofertilizer Rhizobium Azospirillum Azotobacter Mycorrhiza Glomus P cyanobacteria Anabaena Nostoc N feeds crops, eco-friendly sustainable agriculture no pollution cost less soil health better.

Think microbes are tiny invisible workers you cannot see but they cook food, make medicine, clean water, make fuel, protect plants, feed plants all free if we use wisely.