Beneficial Microorganisms

 Microorganisms or microbes are living organisms around us which we normally cannot see with the unaided eye. Some of these, such as the fungus that grows on bread (Rhizopus), can be seen with a magnifying glass. Others cannot be seen without the help of a microscope.

Microorganisms are classified into four major groups- bacteria, fungi, protozoa and some algae. Viruses are also microscopic. They, however, reproduce only inside the cells of the host organism, which may be a bacterium, plant or animal. Common ailments like cold, influenza (flu) and most coughs and serious diseases like polio and chicken pox are caused by viruses. Diseases like dysentery and malaria are caused by protozoa (protozoans) whereas typhoid and tuberculosis (TB) are bacterial diseases.

Microorganisms may be single-celled like bacteria, some algae and protozoa, or multicellular, such as algae and fungi. They can survive under all types of environment, ranging from ice cold climate to hot springs and deserts to marshy lands. They are also found inside the bodies of animals including humans. Some microorganisms grow on other organisms while others exist freely. Microorganisms like amoeba can live alone, while fungi and bacteria may live in colonies.

Microorganisms play an important role in our lives. Some of them are beneficial in many ways whereas some others are harmful and cause diseases.

Beneficial/Friendly Microorganisms
Microorganisms are used for various purposes. They are used in the preparation of curd, bread and cake. Curd contains several microorganisms. Of these, the bacterium, Lactobacillus promotes the formation of curd. It multiplies in milk and converts it into curd. Bacteria are also involved in the making of cheese, pickles and many other food items. Microorganisms have been used for the production of alcohol since ages. They are also used in cleaning up of the environment. For example, the organic wastes (vegetable peels, remains of animals, faeces, etc.) are broken down into harmless and usable substances by bacteria. Bacteria are also used in the preparation of medicines. Antibiotics are produced by various fungi, bacteria, actinomycetes etc. In agriculture they are used to increase soil fertility and control/kill different pests (biopesticides eg. Bacillus thuringiensis -BT)

Commercial Use of Microorganisms
Microorganisms are used for the large scale production of alcohol (Saccharomyces cerevisiae), wine and acetic acid (vinegar) (Acetobacter, Glucunobacter). Yeast  (Saccharomyces cerevisiae) is used in the baking industry for making breads, pastries and cakes and for commercial production of alcohol and wine by growth on natural sugars present in grains like barley, wheat, rice, crushed fruit juices, etc. The process of conversion of sugar into alcohol is known as fermentation. Louis Pasteur discovered fermentation in 1857.

Saccharomyces cerevisiae

Medicinal Use of Microorganisms
Antibiotics kill or stop the growth of the disease-causing microorganisms. A number of antibiotics are being produced from bacteria and fungi. Penicillin (Penicillium notatum), Streptomycin (Streptomyces), tetracycline and erythromycin are some of the commonly known antibiotics which are made from fungi and bacteria. The antibiotics are manufactured by growing specific microorganisms and are used to cure a variety of diseases. Antibiotics are even mixed with the feed of livestock and poultry to check microbial infection in animals. They are also used to control many plant diseases.

Antibiotics should be taken only on the advice of a qualified doctor and it is very important to complete the course prescribed by the doctor. If one takes antibiotics when not needed or in wrong doses, it may result in the development of antibiotic resistant bacteria and make the drug less effective when you might need it in future. Also antibiotics taken unnecessarily may kill the beneficial bacteria in the body.

Antibiotics could be bacteriostatic (stop growth) or bactericidal (kill the organism). 

According to their action, antibiotics could be, antibacterial, antifungal, antiprotozoal etc. Antibiotics are not effective against viruses, since they are the ultimate parasites and have no metabolic machinery of their own. Thus, antibiotics,  are not effective against cold and flu as these are caused by viruses.

Vaccine
Several diseases, including cholera, tuberculosis, smallpox and hepatitis can be prevented by vaccination. Edward Jenner discovered the vaccine for smallpox in 1798. When a disease-carrying microbe enters our body, the body produces antibodies to fight the invader. The body also remembers how to fight the microbe if it enters again. So, if dead or weakened microbes are introduced in a healthy body, the body fights and kills them by producing suitable antibodies. The antibodies remain in the body and we are protected from the disease-causing microbes. This is how a vaccine works.

WHO list of diseases with an available vaccine

Under the Pulse Polio Programme. Polio drops given to children are actually a vaccine. A worldwide campaign against smallpox has finally led to its eradication from most parts of the world. Nowadays vaccines are made on a large scale from microorganisms to protect humans and other animals from several diseases.

Probiotics/Friendly bacteria
Probiotics are often called "good" or "helpful/friendly" bacteria which help keep our gut healthy. Probiotics are live microorganisms that have health benefits such as production of short chain fatty acids, vitamins (B12, K), when consumed such as they improve digestive health, aid digestion and help maintain gut health, reduce depression and promote heart health. They compete for space and food against harmful bacteria and prevent them from colonizing in the gut. They can be found in yogurt and other fermented foods, dietary supplements etc. Lactobacillus, Bifidobacteria are common examples.

Agriculture
Some bacteria and blue green algae are able to fix nitrogen from the atmosphere to enrich soil with nitrogen and increase its fertility. These microbes are commonly called biological nitrogen fixers. Biofertilizers include such commercial preparations of nitrogen fixing (Rhizobium, Blue green algae), phosphate solubilizing microorganisms (mycorrhiza). Microorganisms can also be used as biopesticides to control/kill different pests (eg. Bacillus thuringiensis -BT).

Cleaning the Environment/Bioremediation
The microorganisms decompose dead organic waste of plants and animals converting them into simple substances. These substances are again used by other plants and animals. Microorganisms can also be used to degrade the harmful substances and thereby clean up the environment. Cleaning of oil spills can be done by specially developed superbug (Pseudomonas putida). They also play a role in nutrient recycling and are key to various biogeochemical cycles- carbon, nitrogen, sulphur and phosphorous. 

Microorganisms in Genetic engineering

Microorganisms have a short generation time and they can be used as biofactories for producing different commercially/clinically important products. The genes of interest are inserted into these organisms to create .genetically engineered bacteria which can produce pharmaceuticals such as insulin, human growth hormone, interferons and blood clotting factors.