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.
For more information about Bacteria, read the full article at
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News tagged with bacteria
Plasma produces KO cocktail for MRSA
Nov 26, 2009 |
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MRSA (methicillin-resistant Staphylococcus Aureus) and other drug-resistant bacteria could face annihilation as low-temperature plasma prototype devices have been developed to offer safe, quick, easy and un ...
Over-the-counter eye drops raise concern over antibiotic resistance
Medicine & Health / Medications
Nov 27, 2009 |
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(PhysOrg.com) -- The use of antibiotic eye drops for conjunctivitis has increased by almost half since they became available over the counter at chemists in 2005, data obtained by Oxford University researchers ...
Researchers discover biological basis of 'bacterial immune system'
Nov 25, 2009 |
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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.
Blocking biofilms: Alzheimer's research sheds light on potential treatments for urinary tract infections
Nov 25, 2009 |
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(PhysOrg.com) -- Research into Alzheimer's disease seems an unlikely approach to yield a better way to fight urinary tract infections (UTIs), but that's what scientists at Washington University School of Medicine in St. Louis ...
A sticky solution for identifying effective probiotics
Nov 24, 2009 |
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Scientists have crystallised a protein that may help gut bacteria bind to the gastrointestinal tract. The protein could be used by probiotic producers to identify strains that are likely to be of real benefit to people.
Surface bacteria maintain skin's healthy balance
Nov 22, 2009 |
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On the skin's surface, bacteria are abundant, diverse and constant, but inflammation is undesirable. Research at the University of California, San Diego School of Medicine now shows that the normal bacteria living on the ...
Like humans, ants use bacteria to make their gardens grow
Nov 19, 2009 |
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(PhysOrg.com) -- Leaf-cutter ants, which cultivate fungus for food, have many remarkable qualities.
Cigarettes harbor many pathogenic bacteria: Study
Nov 19, 2009 |
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Cigarettes are "widely contaminated" with bacteria, including some known to cause disease in people, concludes a new international study conducted by a University of Maryland environmental health researcher ...
Scientists guide immune cells with light and microparticles (w/ Video)
Nov 16, 2009 |
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A team led by Yale University scientists has developed a new approach to studying how immune cells chase down bacteria in our bodies. Their findings are described in the November 15 issue of Nature Methods Advanc ...
Simple test could offer cheap solution to detecting landmines
Nov 16, 2009 |
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Scientists have developed a simple, cheap, accurate test to find undetected landmines.
Vaccine against chlamydia not far away
Nov 16, 2009 |
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When a woman becomes infected with Chlamydia, the first white blood cells that arrive at the scene to fight the infection are not the most effective. This is shown by a thesis from the Sahlgrenska Academy. This discovery ...
Researchers discover key to vital DNA, protein interaction
Nov 09, 2009 |
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(PhysOrg.com) -- A researcher at Iowa State University has discovered how a group of proteins from plant pathogenic bacteria interact with DNA in the plant cell, opening up the possibility for what the scientist ...
Scientists visualize how bacteria talk to one another
Nov 08, 2009 |
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Using imaging mass spectrometry, researchers at the University of California, San Diego have developed tools that will enable scientists to visualize how different cell populations of cells communicate. Their ...
Bacteria 'invest' wisely to survive uncertain times, scientists report
Nov 02, 2009 |
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Like savvy Wall Street money managers, bacteria hedge their bets to increase their chances of survival in uncertain times, strategically investing their biological resources to weather unpredictable environments.
Researchers Examine How Viruses Destroy Bacteria
Nov 18, 2009 |
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Viruses are well known for attacking humans and animals, but some viruses instead attack bacteria. Texas A&M University researchers are exploring how hungry viruses, armed with transformer-like weapons, attack bacteria, which ...
