Microbes in Human Welfare

Microbes or microorganisms form a big component of the biological systems of the world. They are ubiquitous, present everywhere – within the soil, around us, in water, the air we breathe, and both in and on our bodies. Animals and plants also contain microbes or microorganisms. They are so tiny, microscopic in nature, varying in shape and size. They can only be seen through the microscope. The different types of microbes are:

• Algae

• Bacteria

• Fungi

• Protozoa

• Virus

Microbes in Human Welfare

There are several useful microorganisms that are beneficial to humans in various ways apart from harmful and infectious disease-causing pathogens. Some of the foremost important contributions of microbes to human welfare are discussed below. 

In Household Products

• Fermentation of milk to prepare yoghurt.

• Milk cuddling to prepare curd, cheese, and paneer.

• Fermentation of dough, which is used for making-idli, and dosa.

• The dough that is used to prepare bread is fermented using Saccharomyces cerevisiae which is also known as baker's yeast.

• ‘Toddy ‘ a traditional south Indian drink is made by fermenting sap from palms.

• Fish, soybean and bamboo shoots are fermented with the help of microbes to produce food.

• A type of cheese - Swiss cheese has huge holes in its texture. These holes are produced by a large amount of CO₂. This CO₂ is produced during the fermentation process because of the bacterium used - Propionibacterium shamanic.

• Another type of cheese called the Roquefort cheese is ripened by growing specific fungi on them. This gives the cheese a particular flavour.

In Industrial Products

• Production of beverages like wine, beer, whiskey, brandy or rum.

• Production of antibiotics like Penicillin and other chemical substances to kill or retard the expansion of disease-causing microbes.

• Few Chemicals, Enzymes and other Bioactive Molecules also are produced by these microbes for various human uses.

Fermented Beverages

• To produce microbes on a large scale for industrial purposes a vessel named fermentor is used.

• The brewer’s yeast (Saccharomyces cerevisiae) is used to produce ethanol. Here the yeast ferments malted cereals and fruit juices.

• The alcohol produced using distillation is wine, whereas the ones that are produced without distillation are whisky, brandy and rum.

Antibiotics

• Antibiotic means “against life” in Greek. These are substances that can kill or destroy the growth of other microbes.

• Penicillin was the first antibiotic discovered from the Staphylococci bacteria by Alexander Fleming.

• Penicillin was named after the moulds Penicillium notatum. It was used to treat soldiers in the USA during WW2.

• Antibiotics today have been developed to treat many deadly diseases like whooping cough, leprosy, diphtheria,  etc.

Chemicals, Enzymes and Other Bioactive Molecules

• A fungus named Aspergillus niger produces citric acid.

• A bacterium named Acetobacter aceti produces acetic acid.

• Another bacterium named Clostridium bretylium produces butyric acid and a bacterium named Lactobacillus produces lactic acid.

• The oily laundry stains are removed using the lipases which are present in the detergent formulations.

• The bottled juices in shops are clarified using pectinases and proteases.

• Streptococcus which produces the streptokinase is used as a clot-buster in medical treatments.

• Trichoderma polysporum produces a bioactive molecule named cyclosporin which helps as an immunosuppressive in organ transplant surgery.

• A yeast named Monascus purpureus produces statins that help lower blood cholesterol levels.

In Sewage Treatment

Sewage is treated in sewage treatment plans (STPs) before disposing of it so as to make it less polluting which is naturally carried out by heterotrophic microbes present in the sewage. The treatment is administered in two stages – primary treatment, secondary treatment or biological treatment.

Primary treatment

• During primary treatment, physical particles are removed from the sewage using the filtration and sedimentation method.

• Initially, the floating debris is removed by filtration.

• After filtration, the soil and rocks in the debris are removed by the process of sedimentation.

• Solids from the primary sludge and the supernatant from the effluent.

Secondary Treatment

• It is also known as biological treatment.

• The effluent from primary treatment is taken forward for the secondary treatment.

• The large aeration tanks here perform the mechanical work and pump air into the tank so as to agitate the effluents.

• This process accelerates the growth of large numbers of aerobic bacteria eventually leading to flocs.

• Flocs are the mesh-like structures formed during the treatment of sewage.

• These processes minimize the demand for biochemical oxygen of the effluent significantly. BOD is the amount of oxygen that might be consumed if all the organic matter in one litre of water were oxidized by the bacteria. The sewage water is treated to reduce the effect of BOD as the BOD gauges the rate of uptake of oxygen by microbes in a water sample. Therefore, BOD may be a measure of the organic matter present in water. The more the demand for biochemical oxygen, the more is its polluting potential.

• The significant decrease in the BOD forces the effluents to pass and settle down in the settling tanks, where they are allowed to sediment.

• This active sludge is then pumped back to aeration tanks and then to larger tanks for the process of anaerobic sludge digestion.

• Anaerobically here the other bacteria and fungus digest the sludge.

In Biogas Production

• Biogas is used as a fuel and is produced by microbial activity. It is a mixture of gasses containing high concentrations of methane.

• Methanobacterium, commonly found in anaerobic sludge, is used to facilitate sewage treatment.

•  They are also found in the rumen of ruminants.

• Thus they help in the process of digestion of cellulose and play a vital role in the nutrition of the cattle.

• The excreta of cattle, also known as Gobar is rich in bacteria and therefore is used for the generation of biogas commonly termed as fertilizer.

As Biocontrol Agents

• The utilization of biological methods to regulate plants pests and diseases is mentioned as biocontrol which has been achieved through chemicals – pesticides and insecticides.

• The use of biocontrol measures will reduce the dependence on toxic chemicals and pesticides to a greater extent.

• Biological farming enhances the life forms like the inhabiting of the sector, pests and predators, life cycles, feeding patterns that help in developing suitable means of biocontrol.

• Bacillus thuringiensis, available as dry spores, sprayed on vulnerable plants are some of the examples of microbial biocontrol agents.

• Genetic engineering developments have enabled scientists to release B. thuringiensis toxins genes into the plant body thereby making them resistant to attacks by insect pests. For example – Bt-cotton.

• Most of the baculoviruses used as biological control agents are within the genus Nucleopolyhedrovirus.

• Microbes are also used as biofertilizers.