Microbes in Human Welfare

About this unit

Microbes are often linked only with disease, but most bacteria, fungi and other microorganisms are harmless and many are extremely useful. This unit shows how microbes help humans at home (curd, bread, cheese), in industry (beverages, antibiotics, enzymes, bioactive molecules), in cleaning wastewater, in producing biogas, and in agriculture as biocontrol agents and biofertilisers. It connects microbiology with everyday life, public health and sustainable farming.

Key ideas

• Lactic acid bacteria (LAB) convert milk into curd and add vitamin B₁₂.
• Baker's yeast (Saccharomyces cerevisiae) leavens dough and ferments sugars into ethanol.
• Antibiotics such as penicillin are produced by microbes and kill or inhibit disease-causing microbes.
• Sewage is treated in two stages: primary (physical) and secondary (biological, using flocs).
• Methanogens such as Methanobacterium produce methane-rich biogas from organic waste.
• Bacillus thuringiensis, Trichoderma and baculoviruses act as biocontrol agents; Rhizobium, Azotobacter, mycorrhiza and cyanobacteria act as biofertilisers.

How to prepare

Make a two-column list of microbe and product (for example, Aspergillus niger and citric acid) and revise it often, because matching questions are common. Learn the flow of sewage treatment and the parts of a biogas plant. Remember which organisms are bacteria, which are fungi and which are viruses.