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.
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News tagged with bacterium
Researcher uses bacteria to make radioactive metals inert
Sep 08, 2009 |
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The Lost Orphan Mine below the Grand Canyon hasn't produced uranium since the 1960s, but radioactive residue still contaminates the area. Cleaning the region takes an expensive process that is only done in ...
'Taco shell' protein: Orientation of middle man in photosynthetic bacteria described
Apr 13, 2009 |
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(PhysOrg.com) -- Researchers at Washington University in St. Louis have figured out the orientation of a protein in the antenna complex to its neighboring membrane in a photosynthetic bacterium, a key find ...
Research could lead to new non-antibiotic drugs to counter hospital infections
Apr 09, 2009 |
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Lack of an adequate amount of the mineral phosphate can turn a common bacterium into a killer, according to research to be published in the April 14, 2009, issue of the Proceedings of the National Academies of ...
Coenzyme rare to bacteria critical to Mycobacterium tuberculosis survival
Mar 23, 2009 |
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Coenzyme F420, a small molecule that helps certain enzymes transfer electrons, is found in microorganisms known as methane-producing archaea, some of which thrive in extreme environments. It also helps the bacterium that ...
Scientists Build Anti-Mosquito Laser
Mar 16, 2009 |
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(PhysOrg.com) -- In an effort to prevent the spread of malaria, scientists have built a laser that shoots and kills mosquitoes. Malaria, which is caused by a parasite and transmitted by mosquitoes, kills about ...
Antibiotic combination defeats extensively drug-resistant TB
Feb 26, 2009 |
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A combination of two FDA-approved drugs, already approved for fighting other bacterial infections, shows potential for treating extensively drug resistant tuberculosis (XDR-TB), the most deadly form of the ...
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.
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 ...
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?
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." ...
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 ...
Important defense against stomach ulcer bacterium identified
Oct 13, 2009 |
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A special protein in the lining of the stomach has been shown to be an important part of the body's defense against the stomach ulcer bacterium Helicobacter pylori in a new study from the Sahlgrenska Academy at the Univer ...
Bacterium helps formation of gold
Oct 07, 2009 |
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Australian scientists have found that the bacterium Cupriavidus metallidurans catalyses the biomineralisation of gold by transforming toxic gold compounds to their metallic form using active cellular mechan ...
Team finds a better way to watch bacteria swim
Oct 04, 2009 |
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Researchers have developed a new method for studying bacterial swimming, one that allows them to trap Escherichia coli bacteria and modify the microbes' environment without hindering the way they move.
