Related topics: proceedings of the national academy of sciences
Bacteria
hideActinobacteria (high-G+C) Firmicutes (low-G+C) Tenericutes (no wall)
Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Deinococcus-Thermus Fusobacteria Gemmatimonadetes Nitrospirae Proteobacteria Spirochaetes Synergistetes
Acidobacteria Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Dictyoglomi Fibrobacteres Planctomycetes Thermodesulfobacteria Thermotogae
The bacteria [bækˈtɪərɪə] (help·info) (singular: bacterium)[α] are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals. Bacteria are ubiquitous in every habitat on Earth, growing in soil, acidic hot springs, radioactive waste, water, and deep in the Earth's crust, as well as in organic matter and the live bodies of plants and animals. There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water; in all, there are approximately five nonillion (5×1030) bacteria on Earth, forming much of the world's biomass. Bacteria are vital in recycling nutrients, with many steps in nutrient cycles depending on these organisms, such as the fixation of nitrogen from the atmosphere and putrefaction. However, most bacteria have not been characterized, and only about half of the phyla of bacteria have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology.
There are approximately ten times as many bacterial cells in the human flora of bacteria as there are human cells in the body, with large numbers of bacteria on the skin and as gut flora. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases, including cholera, syphilis, anthrax, leprosy and bubonic plague. The most common fatal bacterial diseases are respiratory infections, with tuberculosis alone killing about 2 million people a year, mostly in sub-Saharan Africa. In developed countries, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage treatment, the production of cheese and yoghurt through fermentation, as well as in biotechnology, and the manufacture of antibiotics and other chemicals.
Once regarded as plants constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and rarely harbour membrane-bound organelles. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved independently from an ancient common ancestor. These evolutionary domains are called Bacteria and Archaea.
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News tagged with bacteria
Popular diet product recalled in US amid bacteria fears
6 hours ago |
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Millions of cans of a popular ready-to-drink diet product are being recalled in the United States after tests showed the liquid meals could be tainted with bacteria, the manufacturer said Friday.
Newly explored bacteria reveal some huge RNA surprises
Dec 02, 2009 |
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(PhysOrg.com) -- Yale University researchers have found very large RNA structures within previously unstudied bacteria that appear crucial to basic biological functions such as helping viruses infect cells ...
Stopping MRSA before it becomes dangerous is possible, researchers find
Dec 03, 2009 |
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Most scientists believe that staph infections are caused by many bacterial cells that signal each other to emit toxins. The signaling process is called quorum sensing because many bacteria must be present ...
Computer model reveals where food pathogens grow
Dec 03, 2009 |
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(PhysOrg.com) -- An outbreak of food-related illness, such as E. coli-tainted spinach, often leaves food safety experts scratching their heads over the source of the contamination.
2 heads better than 1 in new antibiotic method
Dec 03, 2009 |
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An antibiotic that binds to a well-established target in a novel and unexpected way could be the inspiration for designing new, more potent antibacterial drugs.
Scientists get up close to bacteria's toxic pumps
Nov 30, 2009 |
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Scientists are building a clearer image of the machinery employed by bacteria to spread antibiotic resistance or cause diseases such as whooping cough, peptic stomach ulcers and legionnaires' disease.
Researchers discover biological basis of 'bacterial immune system'
Nov 30, 2009 |
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(PhysOrg.com) -- Bacteria don’t have easy lives. In addition to mammalian immune systems that besiege the bugs, they have natural enemies called bacteriophages, viruses that kill half the bacteria on Earth every two days.
It takes two to infect: Structural biologists shed light on mechanism of invasion protein
Nov 30, 2009 |
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Bacteria are quite creative when infecting the human organism. They invade cells, migrate through the body, avoid an immune response and misuse processes of the host cell for their own purposes. To this end every bacterium ...
Discovery of the Jekyll-and-Hyde factors in 'coral bleaching'
Dec 02, 2009 |
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Scientists are reporting the first identification of substances involved in the Jekyll-and-Hyde transformation that changes harmless marine bacteria into killers that cause "coral bleaching." Their study appears ...
Discovery opens new avenues for treating devastating freshwater fish parasite, 'Ich'
Dec 02, 2009 |
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Researchers from the University of Georgia College of Veterinary Medicine have made an "unexpected" dual discovery that could open new avenues for treating Ichthyophthirius multifiliis, or "Ich", a devastating ...
Physician urges changes in diagnosis for sore throat in young adults
Nov 30, 2009 |
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New analysis from the University of Alabama at Birmingham (UAB) suggests that physicians need to re-think their diagnosis and treatment of sore throat, or pharyngitis, in adolescents and young adults to consider a more newly ...
Scientists gain new understanding of disease-causing bacteria
Nov 30, 2009 |
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A team of scientists from The Forsyth Institute, the University of Connecticut Health Center, the CDC and the Wadsworth Center, have used state-of-the-art technology to elucidate the molecular architecture of Treponema pallidum, ...
