Microbes in Human Welfare: Essential NEET Facts

Lactobacillus converts milk to curd via lactic acid fermentation; also increases vitamin B12 content
Saccharomyces cerevisiae (baker's yeast) produces CO2 (leavening) and ethanol (fermentation)
Propionibacterium shermanii creates holes in Swiss cheese by producing CO2 — NOT Lactobacillus
Penicillium roqueforti is responsible for Roquefort (blue-green) cheese ripening
Aspergillus niger produces citric acid industrially
Acetobacter aceti oxidizes ethanol to acetic acid (vinegar)
Alexander Fleming discovered penicillin from Penicillium notatum in 1928
Streptomyces species produce streptomycin, erythromycin, and tetracycline
Streptokinase is produced by Streptococcus — it is a thrombolytic enzyme (clot-buster), NOT an antibiotic
Lipases and proteases are used in laundry detergents for stain removal
Pectinases (from Aspergillus) clarify fruit juices by breaking down pectin
Lovastatin from Monascus purpureus inhibits HMG-CoA reductase — lowers blood cholesterol
Cyclosporin A from Trichoderma polysporum is an immunosuppressant for organ transplants
Primary sewage treatment = physical (screening + sedimentation); does NOT significantly reduce BOD
Secondary sewage treatment = biological (aeration with aerobic microbes); significantly reduces BOD
BOD (Biochemical Oxygen Demand) = dissolved O2 consumed for microbial decomposition; HIGH BOD = HIGH pollution
Methanobacterium (methanogen) in anaerobic digesters produces biogas: CH4 + CO2 + H2S
Bacillus thuringiensis produces Cry proteins (Cry1Ac, Cry2Ab) toxic to lepidopteran insect larvae
Baculoviruses (NPV) are species-specific biocontrol agents with no impact on non-target organisms
Rhizobium = symbiotic N2 fixation in legume root nodules
Azotobacter / Azospirillum = free-living (non-symbiotic) N2 fixers in soil
Anabaena and Nostoc (cyanobacteria) fix N2 and add organic matter — critical in paddy fields
Glomus (mycorrhiza) enhances phosphorus uptake — it does NOT fix nitrogen