Bacteria are a large group of single-celled microscopic prokaryote organisms that inhabit virtually all environments including the air, soil, water, organic matter, radioactive waste, the earthâ€™s crust, and the bodies of multicellular organisms. Bacteria vary in their cell structure and mode of metabolism. They are categorized as autotrophs, heterotrophs, lithotrophs, organotrophs, chemotrophs or phototrophs, and exist in various cell shapes such as coccus, bacillus, spirochete, and vibrio forms. They can be divided into two main groups, gram-positive or gram-negative, based on the structure of their cell wall and their reaction to the gram stain. Ecologically, these microorganisms are capable of free-living, mutualistic, parasitic or pathogenic existence.
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Bacteria are so numerous and diverse, that new species of bacteria are continually being discovered in the environment, and within the human body, as well as that of other organisms. All the species of bacteria known represent only a tiny fraction of the diverse bacterial species present in nature. Although some bacteria cause food poisoning and infectious diseases in multicellular plants and animals, the vast majority is harmless and many are beneficial to natural processes and also to the proper functioning of higher organisms.
Bacteria are used in various industrial processes, especially the food industry. Numerous manufactured food products are modified biochemically by bacterial growth in the process of fermentation. Fermented foods produced commercially by bacteria include dairy products such as cheese and yoghurt, vegetable products such as sauerkraut and pickles, various forms of cured meats and sausages, vinegar and soy products. Bacteria are also used in the manufacturing of alcoholic beverages like wine made from grapes and other fruits, beer and liquor made from grains, and tequila made from cacti. The benefits of bacterial fermentation of food products include enhanced preservation, increased digestibility, higher nutrient content and improved flavor.
The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria are capable of digesting the hydrocarbons present in petroleum and are thus used in cleaning up oil spills. They can also be altered to produce certain enzymes that metabolize industrial waste components that are toxic to other life forms. Bacteria can also be used in the place of pesticides in specific biological pest control. As a result of this specificity, bacterial pesticides are regarded as environmentally friendly, since they have little or no effect on humans, wildlife, pollinators, and most other beneficial insects. The ability of bacteria to breakdown organic compounds to methane gas is widely employed in treatment of sewage.
In the chemical industry, the manufacture of ethanol, acetone, organic acid, enzymes, and perfumes rely on the use of bacteria. More importantly, bacteria are used in the production of pure chemicals for use as pharmaceuticals or agrochemicals. The discovery of antibiotic drugs made from bacteria, such as cephalosporin, streptomyces, erythromycin and bacitracin have greatly improved the quality of human life in the twentieth century. Steroids and vaccines used in disease prevention are also produced with the use of bacteria.
Because of their ability to grow rapidly and the relative ease with which they can be manipulated, bacteria are the pillars for the fields of molecular biology, genetics and biochemistry. Creating mutations in bacterial DNA and examining the resulting phenotypes, can enable scientists to determine the function of genes, enzymes and metabolic pathways in bacteria, and then apply this knowledge to more complex organisms. This understanding of bacterial metabolism and genetics allows for the use of biotechnology to genetically engineer bacteria for the production of therapeutic proteins such as insulin, interferons, growth factors, or antibodies useful to humans.
Another main role of bacteria is the recycling of nutrients in the environment such as carbon, nitrogen, sulfur and other chemical elements used by living things. Saprophytic species cause decay and decomposition of the nitrogenous remains of dead bodies of plants and animals, converting it to ammonia, while chemosynthetic autotrophs like nitrosomonas and nitrobacter, covert the ammonium compounds in the soil into nitrate salts which can be taken up and used by plants. Bacterial populations especially that of genus Clostridium can be used to separate fibers of jute, hemp, and flax, in a process known as fiber retting. These separated fibers are used to make ropes and sacks. Leather, a widely used product is manufactured by the decomposing action of bacteria on the fats present on the skin of animals.
The human body is home to a wide range of bacterial species, where they constitute normal flora. The beneficial effects of these bacteria which colonize humans are abundant and include: out-competition of harmful microorganisms, synthesis of vitamin B12, B complex and K, immune system enhancement, regulation of digestive health, absorption of minerals like magnesium, formation of new calls and the regeneration of the gastrointestinal tract. Bacteria that reside in the gut of herbivores secrete cellulase, which is useful in the digestion of the cellulose contents of plant cell walls, the main source of nutrients for these animals. Aquatic organisms also benefit from bacteria that cut down growth of algae and reduce noxious odors, making aquatic environments more conducive to living.
It is an undisputed fact that bacteria can and will survive and thrive in the absence of multicellular organisms. Conversely, without the presence of beneficial bacteria, multicellular organisms will be unable to function properly, numerous industrial processes necessary for survival will shut down, and even natural processes like nutrient recycling will cease to occur. The importance of bacteria cannot be over emphasized, and the earth as we know it will definitely take a downward route to degeneration, if bacteria were to cease to exist.