A microbe or microorganism exists in single-celled form or in a colony of cells. Thousands of species of microbes are present in all parts of our body that make up the diverse human microbiome. These are helpful in maintaining and supporting our health, however, if the microbiome is disturbed in some way, certain ailments can be arised such as cardiovascular diseases, autoimmune disorders and cancer.

A question arises- How Do Humans Use Microbes? It is known that microbes are important in health and human culture in a variety of ways. From fermenting foods to treating sewage, from producing fuel and enzymes to other bioactive compounds, microbes have been very helpful in all. Being used as essential tools in biology, microbes are model organisms that have been put to use in bioterrorism and biological warfare. Subjects of Life Sciences such as Biotechnology and Microbiology have been able to spread the importance of microbes for various experimentation and trials. As discussed earlier, microbes make up the human microbiota with the essential gut flora. On the other hand, the pathogens are also responsible for infectious diseases and are often the target of hygiene measures.

Use of Microbes by Humans

Let’s explore more about the use of microbes for humans in varied domains. Following are some of the points that can help us understand in a better manner.

Production of Food

Fermentation process makes use of microorganisms or microbes to produce yoghurt, curd, cheese, ayran and other kinds of food. Providing flavour and aroma, fermentation enhances the quality of food as well as inhibits undesirable organisms. Also, this process is used for bread preparation and preparation of wine and beer. Food making processes such as brewing, baking, pickling and wine making make use of microbes.

Let’s see below what is the role of microbes in the production of certain food products:

Alcoholic Fermentation: Yeast converts sugar, grape juice or grains into alcohol. A mold can also convert starch into sugar and result in formation of the Japanese rice wine.
Vinegar: Bacteria converts alcohol into acetic acid, giving acidic taste to vinegar.
Cheese: The flavour and appearance of a specific kind of cheese is due to the presence of numerous microorganisms associated in it.
Vitamins: Vitamins such as B2, C and B12 use microorganisms for their production.
Antibiotics: Microbes are also used to prepare antibiotics.

2. Treatment of Water

Contaminated water is often cleaned up with microbes as these can respire the dissolved organic substances. It may be aerobic respiration with the help of a well-oxygenated filter bed like a slow sand filter. Methanogens undergo anaerobic digestion and generate methane gas as a by-product which is quite useful.

3. Generation of Energy

Fermentation produces ethanol with the help of microbes as well as produces methane in biogas reactors. This way, various bacteria convert agricultural and urban waste into useful fuels and help in energy generation.

4. Production of Chemicals and Enzymes

Microbes are often used in commercial and industrial levels to produce enzymes, chemicals and bioactive molecules. Microbes such as acetic acid bacteria, butyric acid, Lactobacillus and Aspergillus niger help in microbial fermentation on a large industrial scale to produce organic acids. Bioactive molecules such as Streptokinase are produced from the bacterium Streptococcus and Statins are produced from the yeast Monascus purpureus.

5. Application in Science

Being essential tools in Life Sciences such as Biochemistry, Biotechnology, Genetics and Molecular Biology, microbes are of great importance. Important model microbes in Science are Saccharomyces cerevisiae (yeast) and Schizosaccharomyces pombe (yeast) and they are simple eukaryotes which can be obtained in large numbers and manipulated. Therefore, these are highly valuable in Genomics, Genetics and Proteomics.

6. Importance in Warfare

Microbes have been used as biological warfare, be it for spreading pathogens into castles in earlier days or using microbes for bioterrorism such as the release of Anthrax in the year 1993 in Tokyo.

7. Enrichment of Soil

Making nutrients and minerals in the soil suitably available to the plants, microbes also produce hormones facilitating growth and stimulating the plant immune system and dampening stress responses. It results in fewer diseases and higher yield of the plants with diverse sets of soil microbes.

8. Human Health

Microorganisms share an endosymbiotic relationship with humans as microbial symbiosis helps in enhancing our immune system and microbes depend on our body for their survival and food. Synthesis of vitamins such as biotin and folic acid is supported by the gut flora as well as these help in fermenting the complex and indigestible carbohydrates in our gastrointestinal tract. Also, food supplements or additives and probiotics consisting of microbes are helpful to us.

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FAQs on How Do Humans Use Microbes?

1. What are some key examples of how microbes are used in everyday household products?

Microbes are integral to preparing many common household foods. Here are a few key examples:

Curd: Lactic Acid Bacteria (LAB) like Lactobacillus ferment lactose (milk sugar) into lactic acid. This process coagulates and partially digests milk proteins, converting milk into curd.
Dough: Baker's yeast, Saccharomyces cerevisiae, is used to ferment dough for making bread, idli, and dosa. The fermentation process releases carbon dioxide gas, which causes the dough to rise and gives it a soft, spongy texture.
Cheese: Specific bacteria and fungi are used to ripen cheese, developing its characteristic texture, flavour, and aroma. For example, the large holes in Swiss cheese are due to CO2 production by the bacterium Propionibacterium shermanii.
Toddy: This traditional drink from southern India is made by fermenting sap from palm trees with naturally occurring yeasts.

2. What is the importance of microbes in the industrial production of antibiotics and fermented beverages?

Microbes are essential for large-scale industrial production of valuable compounds like antibiotics and beverages. Their importance lies in their ability to carry out specific biochemical reactions efficiently.

Antibiotics: These are chemical substances produced by some microbes that can kill or inhibit the growth of other disease-causing microbes. For example, Penicillin was the first antibiotic discovered, produced by the fungus Penicillium notatum. Antibiotics are now produced on an industrial scale in large fermenters to treat bacterial infections.
Fermented Beverages: Yeast, particularly Saccharomyces cerevisiae, is used to produce beverages like wine, beer, whisky, and rum. It ferments malted cereals and fruit juices to produce ethanol. The type of beverage depends on the raw material used and the type of processing (with or without distillation).

3. How do microbes play a crucial role in sewage treatment plants (STPs)?

Microbes are fundamental to making municipal wastewater less polluted in Sewage Treatment Plants (STPs). Their role is most critical in the secondary treatment or biological treatment stage. After primary treatment removes large debris and grit, the effluent is passed into large aeration tanks. Here:

Aerobic microbes are encouraged to grow into masses of bacteria and fungal filaments called flocs.
These microbes consume the major part of the organic matter in the effluent as they grow.
This significantly reduces the Biochemical Oxygen Demand (BOD) of the wastewater. A lower BOD indicates less pollution.
The treated effluent is then passed into a settling tank where the bacterial flocs sediment, and the purified water is released into natural water bodies.

4. Why are microbes considered essential for sustainable agriculture as biofertilisers and biocontrol agents?

Microbes are essential for sustainable agriculture because they offer a natural, non-polluting alternative to chemical fertilisers and pesticides.

As biofertilisers, microbes enrich the nutrient quality of the soil. For example, bacteria like Rhizobium (in legume root nodules) and free-living bacteria like Azotobacter fix atmospheric nitrogen into organic forms that plants can use. Fungi like Glomus form mycorrhizal associations with plants, helping them absorb phosphorus from the soil.
As biocontrol agents, microbes are used to control insect pests and diseases, reducing the reliance on toxic chemicals. For example, the bacterium Bacillus thuringiensis (Bt) produces a toxin that kills insect larvae like caterpillars but is harmless to other animals and humans.

Using these microbial agents helps maintain long-term soil health and biodiversity, which is a core principle of sustainable farming.

5. What is the difference between primary and secondary treatment of sewage, and what is the specific role of microbes in each stage?

Primary and secondary treatments are two distinct stages in sewage processing with different mechanisms and microbial involvement.

Primary Treatment: This is a physical process. It involves the removal of large and small particles from sewage through filtration and sedimentation. Floating debris is removed by sequential filtration, and then grit (soil and small pebbles) is removed by sedimentation. All solids that settle form the primary sludge. Microbes have no active role in this stage.
Secondary Treatment: This is a biological process where microbes are actively used. The primary effluent is passed into large aeration tanks where aerobic microbes (flocs) consume organic waste, reducing the BOD. The effluent is then settled, and a small part of the activated sludge (containing microbes) is used as an inoculum for the next batch. Therefore, the specific role of microbes is to biologically degrade organic matter, thus purifying the water.

6. How is biogas produced from organic waste using microbes, and what makes it a superior fuel?

Biogas is produced through the anaerobic (in the absence of oxygen) digestion of organic waste by a group of bacteria called methanogens, such as Methanobacterium. The process occurs in a biogas plant and involves three main steps:

Solubilisation: Complex organic matter like cellulose is broken down into simpler soluble compounds.
Acidogenesis: Bacteria convert these simple compounds into organic acids.
Methanogenesis: Methanogenic bacteria act on the organic acids to produce a mixture of gases, primarily methane (CH₄), along with carbon dioxide (CO₂) and hydrogen (H₂).

Biogas is considered a superior fuel because it is clean (burns without smoke), has a high calorific value, and is a renewable source of energy that also helps in waste management.

7. What are statins and cyclosporin A, and which microbes are used to produce them?

Statins and cyclosporin A are bioactive molecules produced by microbes that have significant medical applications.

Statins: These are blood-cholesterol-lowering agents. They act by competitively inhibiting the enzyme responsible for cholesterol synthesis in the body. Statins are produced by the yeast Monascus purpureus.
Cyclosporin A: This is an immunosuppressive agent used in organ transplant patients to prevent the body from rejecting the new organ. It is produced by the fungus Trichoderma polysporum.