Economic importance of bacteria

Sourdough bread is made to rise by fermentation, with a leaven that consists of bacteria, often combined with wild yeast enzymes.[1] The milk-souring bacterial genus Lactobacillus is used to make yogurt and cheese. Bacteria are used, too, to form organic acids in pickles and vinegar.[2]

Biotechnology involves the use of microorganisms including bacteria and fungi in the manufacturing and services industries. These include chemical manufacturing such as ethanol, acetone, organic acid, enzymes, and perfumes. Bacteria are important in the production of many dietary supplements and pharmaceuticals. For example, Escherichia coli is used for commercial preparation of riboflavin and vitamin K.[3] E. coli is also used to produce D-amino acids such as D-p-hydroxyphenylglycine, an important intermediate for synthesis of the antibiotic amoxicillin.[4]

A vial of insulin

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.[5] Bacterial cells are transformed and used in production of commercially important products. Examples include production of human insulin (used to treat diabetes)[6] and human growth hormone (somatotrophin used to treat pituitary dwarfism).[7]

Dew retting of flax

Bacteria such as Clostridium butyricum 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 spread out on the ground, where they become wetted by dew and ret naturally. These separated fibres are used to make ropes, sacks etc.[8]

Bacteria can also be used in the place of pesticides in biological pest control. This commonly uses Bacillus thuringiensis (also called BT), a Gram-positive, soil-dwelling bacterium. This bacterium 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 effect on humans, wildlife, pollinators, or other beneficial insects.[9]

Alcanivorax borkumensis is capable of degrading oil in seawater

Bacteria can be used to remove pollutants from contaminated water, soil and subsurface material.[10][11] During the Mega Borg Oil Spill, for example, 100 pounds of bacteria were sprayed over an acre of the oil slick to break down the hydrocarbons present into more benign by-products.[12]

Bacteria living in the gut of cattle, horses and other herbivores, for example Ruminococcus spp., help digest cellulose by secreting the enzyme cellulase.[13] This is how herbivores are able get the energy they need from grass and other plants.[14]

Also, Escherichia coli, part of the intestinal microbiota of humans and other animals, converts consumed food into vitamin K₂. This is absorbed in the colon and, in animal models, is sufficient to meet their daily requirement of the vitamin.[15]

A person with severe dehydration due to cholera

Bacteria cause a wide range of diseases in humans and other animals. These include superficial infections (eg. impetigo),[16] systemic infections (eg. typhoid fever),[17] acute infections (eg. cholera)[18] and chronic infections (eg. tuberculosis).[19]

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 difficult to control because of the shortage of chemical control agents for bacteria.[20]

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.[21]