Microbes In Human Welfare

• Microbes are major components of biological systems on Earth, present in soil, water, air, inside bodies of animals and plants
• Microbes are found in extreme environments like deep inside geysers, in highly acidic environments, and under layers of snow
• Microbes are diverse, including protozoa, bacteria, fungi, microscopic animal and plant viruses, viroids, and prions
• Some microbes can be grown on nutritive media to form colonies visible to the naked eye, useful for studies on microorganisms
• Microbes play a crucial role in human welfare, with significant contributions in household products, industrial products, sewage treatment, biogas production, biocontrol agents, and biofertilisers
• Microbes like bacteria and fungi are used in household products such as curd, fermented dough for foods like dosa and idli, and traditional drinks and foods
• In industrial products, microbes are used to synthesize beverages like wine, beer, whisky, brandy, rum, and antibiotics
• Antibiotics produced by microbes have greatly contributed to human welfare by treating diseases caused by other microbes
• Microbes are also used for commercial and industrial production of chemicals, enzymes, and bioactive molecules like organic acids, alcohols, lipases, and clot busters
• Microbes play a vital role in sewage treatment processes, helping in the breakdown of waste materials in large quantities of wastewater
• Sewage treatment involves two stages: primary treatment and secondary treatment
• Primary treatment:

  • Involves physical removal of particles from sewage through filtration and sedimentation
  • Sequential filtration removes floating debris
  • Sedimentation removes grit like soil and small pebbles
  • Solids that settle form primary sludge, while the supernatant forms effluent
• Secondary treatment or Biological treatment:

  • Primary effluent is passed into large aeration tanks where it is agitated mechanically and air is pumped into it
  • Useful aerobic microbes grow into flocs, consuming organic matter in the effluent
  • This reduces the BOD (biochemical oxygen demand) of the effluent
  • BOD measures the rate of oxygen uptake by microorganisms in water, indicating organic matter present
  • Effluent is treated until BOD is reduced significantly
• Activated sludge:

  • Part of activated sludge is pumped back into the aeration tank as inoculum
  • Major part of sludge is pumped into anaerobic sludge digesters
  • Anaerobic bacteria digest sludge, producing gases like methane, hydrogen sulphide, and carbon dioxide
  • These gases form biogas, a source of energy
• Effluent from secondary treatment plant is released into natural water bodies like rivers and streams
• Biogas production:

  • Biogas is a mixture of gases, predominantly methane, produced by microbial activity
  • Methanogens, like Methanobacterium, produce methane during anaerobic growth on cellulosic material
  • Methanogens are found in anaerobic sludge during sewage treatment
• Biogas plant:

  • Consists of a concrete tank where bio-wastes are collected and dung slurry is fed
  • Floating cover rises as gas is produced due to microbial activity
  • Outlet pipe supplies biogas to nearby houses
  • Spent slurry can be used as fertilizer
  • Biogas is used for cooking and lighting
• Biological control of pests and diseases:

  • Relies on natural predation instead of chemicals
  • Organic farming promotes biodiversity to control pests at manageable levels
  • Aims to understand interactions between organisms in ecosystems
• The use of biocontrol measures greatly reduces dependence on toxic chemicals and pesticides
• Biological farming involves becoming familiar with various life forms in the field, including predators, pests, their life cycles, feeding patterns, and habitats
• Ladybirds and Dragonflies are useful for getting rid of aphids and mosquitoes, respectively
• Microbial biocontrol agents like Bacillus thuringiensis (Bt) can be used to control butterfly caterpillars
• Bt toxin genes have been introduced into plants through genetic engineering to make them resistant to insect pests
• Trichoderma, a fungus, is being developed as a biological control for plant diseases
• Baculoviruses, specifically Nucleopolyhedrovirus, are used as biological control agents against insects and arthropods
• Baculoviruses have no negative impacts on plants, mammals, birds, fish, or non-target insects
• Biofertilisers, like bacteria, fungi, and cyanobacteria, enrich the nutrient quality of the soil
• Rhizobium bacteria fix atmospheric nitrogen into organic forms for leguminous plants
• Fungi form symbiotic associations with plants, like mycorrhiza, to absorb phosphorus from the soil
• Cyanobacteria, such as Anabaena and Nostoc, fix atmospheric nitrogen and serve as biofertilisers
• Microbes play a crucial role in various aspects of human welfare, from food production to environmental sustainability