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
Time in a bottle: Scientists watch evolution unfold
Oct 18, 2009 |
4.6 / 5 (42) |
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A 21-year Michigan State University experiment that distills the essence of evolution in laboratory flasks not only demonstrates natural selection at work, but could lead to biotechnology and medical research ...
Evolution of the appendix: A biological 'remnant' no more
Aug 20, 2009 |
4.9 / 5 (29) |
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The lowly appendix, long-regarded as a useless evolutionary artifact, won newfound respect two years ago when researchers at Duke University Medical Center proposed that it actually serves a critical function. ...
Ancient ecosystem thrives millions of years below Antarctic glacier
Space & Earth / Earth Sciences
Apr 16, 2009 |
4.7 / 5 (24) |
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(PhysOrg.com) -- A reservoir of briny liquid buried deep beneath an Antarctic glacier supports hardy microbes that have lived in isolation for millions of years, researchers report this week in the journal ...
Komodo even more deadly than thought: Research
May 18, 2009 |
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The carnivorous reptiles (Varanus komodoensis) are known to bite prey and release them, leaving them to bleed to death from their wounds: the victims are reported to go into shock before the dragons kill a ...
Daily bathroom showers may deliver face full of pathogens, says study
Sep 14, 2009 |
4.6 / 5 (18) |
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While daily bathroom showers provide invigorating relief and a good cleansing for millions of Americans, they also can deliver a face full of potentially pathogenic bacteria, according to a surprising new ...
Bacteria offer insights into human decision making
Dec 08, 2009 |
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(PhysOrg.com) -- Scientists studying how bacteria under stress collectively weigh and initiate different survival strategies say they have gained new insights into how humans make strategic decisions that ...
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 ...
Scientists finding sink holes in Great Lakes
May 04, 2009 |
4.8 / 5 (15) |
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Scientists studying submerged sinkholes in the Great Lakes off the coast of northern Michigan have stumbled onto something they never expected to find: life forms akin to those found in some of Earth's most extreme environments.
Evolution still scientifically stable
Sep 14, 2009 |
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An international team of researchers, including Monash University biochemists, has discovered evidence at the molecular level in support of one of the key tenets of Darwin's theory of evolution.
Newly explored bacteria reveal some huge RNA surprises
Dec 02, 2009 |
4.9 / 5 (12) |
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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 ...
Scientists visualize how bacteria talk to one another
Nov 08, 2009 |
4.8 / 5 (11) |
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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 can plan ahead
Jun 17, 2009 |
4.6 / 5 (11) |
1
Bacteria can anticipate a future event and prepare for it, according to new research at the Weizmann Institute of Science. In a paper that appeared today in Nature, Prof. Yitzhak Pilpel, doctoral student Amir Mitchell and re ...
Researchers identify mechanism that helps bacteria avoid destruction in cells
Oct 10, 2009 |
4.6 / 5 (11) |
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Infectious diseases currently cause about one-third of all human deaths worldwide, more than all forms of cancer combined. Advances in cell biology and microbial genetics have greatly enhanced understanding of the cause and ...
First step to converting solar energy using 'artificial leaf'
Jun 29, 2009 |
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An international team of researchers has modified chlorophyll from an alga so that it resembles the extremely efficient light antennae of bacteria. The team was then able to determine the structure of these light antennae. ...
Comprehensive understanding of bacteria could lead to new insights into many organisms
Sep 25, 2009 |
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(PhysOrg.com) -- Investigators at Burnham Institute for Medical Research, University of California, San Diego, The Scripps Research Institute, Genomics Institute of the Novartis Research Foundation and other ...
