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
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.
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 ...
Wildlife as a source for livestock infections
Oct 07, 2009 |
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A bacterium possibly linked to Crohn's disease could be lurking in wild animals. According to research published in the open access journal BMC Microbiology, Mycobacterium avium subspecies paratuberculosis (Map), can be transm ...
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.
New drug shows promise in the fight against malignant melanoma
Sep 29, 2009 |
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(PhysOrg.com) -- Gavin Robertson is not a man who uses the word ‘hate’ lightly, but he makes no secret of his desire to slay the dragon that is malignant melanoma.
C. difficile hypervirulence genes identified
Sep 25, 2009 |
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Five genetic regions have been identified that are unique to the most virulent strain of Clostridium difficile (C. difficile), the hospital superbug. Researchers writing in BioMed Central's open access journal Genome Biolog ...
Scientists get detailed glimpse of chemoreceptor architecture in bacterial cells
Sep 24, 2009 |
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Using state-of-the-art electron microscopy techniques, a team led by researchers from Caltech has for the first time visualized and described the precise arrangement of chemoreceptors—the receptors that sense ...
New test quickly ID's active TB in smear-negative patients
Sep 23, 2009 |
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Active tuberculosis can be rapidly identified in patients with negative sputum tests by a new method, according to European researchers. Active tuberculosis (TB) is the seventh-leading cause of death worldwide, and while ...
A boy for every girl? Not even close
Sep 10, 2009 |
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In a perfect world, for every boy there would of course be a girl, but a new study shows that actual sex ratios can sometimes sway very far from that ideal. In fact, the male-to-female ratio of one tropical butterfly has ...
