Microbes In Human Welfare

Microbes are microscopic organisms, that can be classified under protozoa, bacteria, fungi, and microscopic plants viruses, viroid, and prions (proteinaceous infectious agents). They are present everywhere– in soil, water, and air, inside our bodies, animals, and plants. Not only in life forms, but they are also present in non-life forms that exist as deep inside the geysers (thermal vents) where the temperature may be as high as 1000℃, deep in the soil, under snow, highly acidic environments, etc. They can be made visible if grown on nutritive media to form colonies. These microbes can be harmful (pathogen) and beneficial to human welfare.

Application of Microbes to Human Welfare

Microbes are used in various procedures which directly or indirectly help humans in various ways:

In Household Products 

1. Curd formation: Lactobacillus bacteria commonly called lactic acid bacteria (LAB) helps in the formation of curd from milk. Curd consists of vitamin B12 and is very beneficial for the stomach. 
2. Fermented food: Bacteria such as Leuconostoc mesenteroides, Streptococcus faecalis, Lactobacillus fermentum, and Bacillus amyloliquefaciens helps in the fermentation of dough which in turn is used for making idli and dosa. They are used for fermenting fish, soybean, and bamboo shoots. Yeast (Saccharomyces cerevisiae) is used in the fermentation of dough that makes bread fluffy.
3. Traditional drink: They are used in making traditional drinks like ‘Toddy’ by fermenting sap from palms.
4. Cheese formation: They are also used in the formation of cheese. For example, the large holes in ‘Swiss cheese’ are due to the production of a large amount of CO₂ by a bacterium named Propionibacterium sharmanii. The ‘Roquefort cheese’ are ripened by growing a specific fungus on them, which gives them a particular flavor.

In Industrial Products

1. Formation of beverages: They are used in the synthesis of beverages like wine, beer, whisky, brandy, or rum on a large scale.
2. Formation of alcohol (ethanol): Yeast (Saccharomyces cerevisiae) is used for the fermentation of malted cereals and fruit juices, to produce alcohol (ethanol) which is an industrial product.
3. Formation of antibiotics: They are used in making antibiotics to treat diseases. For example- penicillin was formed from the fungus Penicillium notatum. Penicillin was the first antibiotic and was discovered by Alexander Fleming. 
4. Production of chemicals: They are used for commercial and industrial production of certain chemicals like organic acids. For example-Aspergillus, niger (a fungus) produces citric acid, Acetobacter aceti (a bacterium) produces acetic acid, Clostridium butylicum (a bacterium) produces butyric acid and Lactobacillus (a bacterium) lactic acid.
5. Production of enzymes: They are used in the production of enzymes. For example-Lipases are used in detergent formulations and are helpful in removing oily stains from the laundry. Similarly, pectinases and proteases are used to clarify bottled juices.
6. Formation of clot buster: They are used in removing clots from the blood vessels of patients who have undergone myocardial infarction leading to a heart attack. For example- the bacterium Streptococcus produces Streptokinase which is used as a ‘clot buster’ means remove clots from the blood vessels. 
7. Immunosuppressive agents: They are used as immunosuppressive agents in organ-transplant patients. For example-cyclosporin A is an immunosuppressive agent which is produced by the fungus Trichoderma polysporum. 
8. Blood cholesterol-lowering agents: Yeast Monascus purpureus produces statins that are used as blood-cholesterol-lowering agents.

In Sewage Treatment

Production of biogas: Sewage consists of large amounts of organic matter (feces, urine, wastewater from toilets, etc.) and microbes (bacteria, fungi, etc.). Some bacteria in sewage grow anaerobically and digest the bacteria and the fungi and produces a mixture of inflammable gases such as methane, hydrogen sulfide, and carbon dioxide. These gases form biogas and can be used as fuel.  Bacteria that produce methane gas along with CO₂ and H₂ are called methanogens (example-Methanobacterium). These methanogens act on cellulosic material either present in sewage or the rumen (a part of the stomach) of cattle. In the rumen, these bacteria help in the breakdown of cellulose and play an important role in the nutrition of cattle.

Microbes as Biocontrol Agents

Biocontrol agents are those biological organisms that can be used to control pests that cause plant diseases. These organisms can be predators (beetle, dragonflies, eagles, etc.) that eat or kill prey (pests), bacteria, fungi, viruses, etc.

• Insects as biocontrol agents: Ladybird beetle (red and black markings) and dragonflies can be used to kill aphids and mosquitoes respectively.
• Bacteria as biocontrol agents: Brassicas and fruit trees are eaten up by butterfly larvae. So, to prevent these trees, butterfly larvae need to be killed. This can be done with the help of bacteria called Bacillus thuringiensis (Bt). The spores of these bacteria mixed with water are available in the market in form of sachets. When this mixture is sprayed on trees or plants, butterfly larvae ingest it. When this bacteria, goes into the gut of the larvae, the toxin is released from bacteria called Bt toxin (Bacillus thuringiensis), and the larvae get killed. This is how bacterial disease will kill the larvae. This bacterium is insect-specific and therefore leaves other insects unharmed. As genetic engineering developed, scientists introduced Bacillus thuringiensis toxin genes into plants. These kinds of plants are resistant to attack by insect pests. So, this help in controlling butterfly caterpillars.
• Fungi as biocontrol agents: Fungus Trichoderma as a microbe is used as a biological control agent for the treatment of plant disease.
• Viruses as biocontrol agents: Baculoviruses (genus Nucleopolyhedrovirus) are pathogens that attack insects and other arthropods. They have no negative impacts on plants, mammals, birds, fish, or even on non-target insects..