Related topics: protein , immune system , bacteria , tuberculosis
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
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with bacterium
Heme channel found
19 hours ago |
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In some ways a cell in your body or an organelle in that cell is like an ancient walled town. Life inside either depends critically on the intelligence of the gatekeepers.
Bacterial protein mimics its host to disable a key enzyme (w/ Video)
Dec 11, 2009 |
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(PhysOrg.com) -- Bacteria use all sorts of cunning to trick hosts into doing their bidding. One con in their bag of tricks: the molecular mimic. In this ruse, bacteria or their agents look for all purposes like some native ...
One Can Act Without Group Support; Even in the Bacterial World
Dec 08, 2009 |
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(PhysOrg.com) -- A single bacterium can act alone, performing the same kinds of actions that a group normally does. The behavior of that bacterium can be manipulated at the cellular level. That’s the intriguing ...
Cholera bacteria show adaptability to changing environments
Dec 08, 2009 |
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(PhysOrg.com) -- The deadly bacterium behind cholera epidemics spends only a fraction of its life infecting humans. Most of the time, Vibrio cholerae lurks in estuaries and other semisalty aquatic habitats.
Scientists chase deadly MRSA bacteria with new models
Dec 07, 2009 |
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(PhysOrg.com) -- Ten years ago, Chicago hospitals were at ground zero when the deadly MRSA bacterium, till then confined to hospitals, learned some new tricks and spilled out into the community. This year, ...
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 ...
Biologists discover bacterial defense mechanism against aggressive oxygen
Nov 20, 2009 |
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Bacteria possess an ingenious mechanism for preventing oxygen from harming the building blocks of the cell. This is the new finding of a team of biologists that includes Joris Messens of VIB, a life sciences research institute ...
With Help from a Bacterium, Cockroaches Develop Way to Store Excess Uric Acid
Nov 12, 2009 |
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(PhysOrg.com) -- What life form can use materials as nutrients that we, and most other animals, would consider waste products?
Sweet as can be: How E. coli gets ahead
Nov 12, 2009 |
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Scientists at the University of York have discovered how certain bacteria such as Escherichia coli have evolved to capture rare sugars from their environment giving them an evolutionary advantage in naturally competitive enviro ...
New insight into predicting cholera epidemics in the Bengal Delta
Nov 04, 2009 |
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Cholera, an acute diarrheal disease caused by the bacterium Vibrio cholerae, has reemerged as a global killer. Outbreaks typically occur once a year in Africa and Latin America. But in Bangladesh the epidemics occur twice ...
There's a speed limit to the pace of evolution, biologists say
Nov 02, 2009 |
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Researchers at the University of Pennsylvania have developed a theoretical model that informs the understanding of evolution and determines how quickly an organism will evolve using a catalogue of "evolutionary speed limits." ...
Deadly stomach infection rising in community settings, study finds
Oct 26, 2009 |
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Mayo Clinic researchers have found that a sometimes deadly stomach bug, Clostridium difficile, is on the rise in outpatient settings. Clostridium difficile is a serious bacteria that can cause symptoms ranging from diarrhea ...
Synthetic Cells Shed Biological Insights While Delivering Battery Power
Oct 20, 2009 |
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(PhysOrg.com) -- Trying to understand the complex workings of a biological cell by teasing out the function of every molecule within it is a daunting task. But by making synthetic cells that include just a ...
Protein interaction network can respond Helicobacter pylori infection?
Oct 16, 2009 |
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Helicobacter pylori (H pylori) is a gram negative bacterium which infects about 50% of the world population. H pylori colonization causes a strong systemic immune response. Various tools have been employed to identify the rela ...
Bacterium Identified as Potato Disease Culprit
Oct 14, 2009 |
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(PhysOrg.com) -- Studies tying a new species of Candidatus Liberibacter bacteria to zebra chip (ZC) disease in potato should speed efforts to better protect the tuber crop from costly outbreaks.
