Economic importance of bacteria
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Bacteria are economically important as these microorganisms are used by humans for many purposes and are harmful in causing disease and spoiling food. The beneficial uses of bacteria include the production of traditional foods such as yoghurt, cheese, and vinegar; biotechnology and genetic engineering, producing substances such as drugs and vitamins; agriculture; fibre retting; human and animal digestion; and biological control of pests.
Biotechnology is the use of microorganisms such as bacteria, fungi and algae for the manufacturing and services industries. These include chemical manufacturing such as ethanol, acetone, organic acid, enzymes, and perfumes. In the chemical industry, bacteria are most important in the production pharmaceuticals.
Genetic engineering is the manipulation of genes. It is also called recombinant DNA technology. In genetic engineering, pieces of DNA (genes) are introduced into a host by a variety of techniques, one of the earliest being the use of a virus vector. The foreign DNA becomes a permanent feature of the host, and is replicated and passed on to daughter cells along with the rest of its DNA. Bacterial cells are transformed and used in production of commercially important products. The examples are production of human insulin (used against diabetes), human growth hormone (somatotrophin used to treat pituitary dwarfism), and infections which can be used to help fight viral diseases.
Bacteria play many roles in agriculture from biodegradation to food production. Bacteria are often employed in the dairy industry for making yoghurt, ripening cheese and giving certain dairy products a specific aroma. Bacteria including Bacillus aceti convert wine or beer into vinegar.
Bacteria are used to separate fibres of jute, hemp, and flax in the process of retting. The plants are immersed in water and when they swell, inoculated with bacteria which hydrolyze pectic substances of the cell walls and separate the fibres. Alternatively the plants are left spread out on the ground, wetted by the dew, to ret naturally. These separated fibres are used to make ropes and sacks etc.
Some bacteria living in the gut of cattle, horses and other herbivores secrete cellulase, an enzyme that helps in the digestion of the cellulose contents of plant cell walls. Cellulose is the major source of energy for these animals. Generally plant cells contain cellulose. The bacteria present in the stomach of cattle will help in the digestion of cellulose.
The Escherichia coli (E-coli) that lives in the human large intestine synthesizes vitamin B and releases it for human use. Similarly, Clostridium butyclicum is used for commercial preparation of riboflavin, and vitamin B & vitamin k.
Bacteria can also be used in the place of pesticides in the biological pest control. This commonly uses Bacillus thuringiensis (also called BT), a Gram-positive, soil dwelling bacterium. This bacteria is used as a Lepidopteran-specific insecticide under trade names such as Dipel and Thuricide. Because of their specificity, these pesticides are regarded as Environmentally friendly, with little or no effect on humans, wildlife, pollinators, and most other beneficial insects.
Some bacteria are harmful and act either as disease-causing agents (pathogens) both in plants and animals, or may play a role in food spoilage.
Agents of disease
Organisms which cause disease are called pathogens. Some bacteria are pathogenic and cause diseases both in animals and plants. However, pathogenic bacteria more commonly affect animals than plants. Certain bacteria in the normal flora on skin and in the mouth and human intestine cause disease when imbalances have weakened the immune system.
Plant diseases caused by bacteria are commercially important worldwide for agriculture. Besides bacterial pathogens that are already established in many areas, there are many instances of pathogens moving to new geographic areas or even the emergence of new pathogen variants. In addition, bacterial plant pathogens are particularly difficulg to control because of the shortage of chemical control agents for bacteria, apart from antibiotics. However, the use of antibiotics is restricted in many countries due to the potential for evolution of antibiotic resistance and the transmission of antibiotic resistance to bacteria that can cause human disease.
Saprotrophic bacteria attack and decompose organic matter. This characteristic has posed a problem to mankind as food such as stored grains, meat, fish, vegetable and fruits are attacked by saprotrophic bacteria and spoiled. Similarly milk and products are easily contaminated by bacteria and spoiled.