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
Bacteria mix it up at the microscopic level
Nov 02, 2009 |
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(PhysOrg.com) -- Many hands -- or many flagella -- make light work. In studies of the motion of tiny swimming bacteria, scientists at the U.S. Department of Energy's Argonne National Laboratory found that ...
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.
Bacteria 'launch a shield' to resist attack
Nov 02, 2009 |
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Bacteria that cause chronic lung infections can communicate with each other to form a deadly shield against the body's natural defenses. Studying these interactions could lead to new ways of treating bacteria that are resistant ...
Fibre may keep asthma, diabetes at bay, study finds
Oct 28, 2009 |
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Insoluble dietary fibre, or roughage, not only keeps you regular, say Australian scientists, it also plays a vital role in the immune system, keeping certain diseases at bay.
Scientists discover, patent, sell waste-water tech
Oct 26, 2009 |
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Sam Houston State University has applied for six federal patents, three of which have already been awarded, to protect the technology and engineering associated with a "revolutionary" packaged wastewater treatment system ...
Animals now picking up bugs from people, study shows
Oct 26, 2009 |
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Globalisation and industrialisation are causing diseases to spread from humans to animals, a study has shown.
Immune system quirk could lead to effective tularemia vaccine
Oct 22, 2009 |
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Immunologists at the University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh of UPMC and the have found a unique quirk in the way the immune system fends off bacteria called Francisella tularensis, ...
Scientists first to see RNA network in live bacterial cells
Oct 22, 2009 |
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Scientists who study RNA have faced a formidable roadblock: trying to examine RNA's movements in a living cell when they can't see the RNA. Now, a new technology has given scientists the first look ever at RNA in a live ...
Eating right, not supplements, is best at keeping your good bacteria healthy, dietitian says
Oct 21, 2009 |
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Healthy eating, not supplements, is the best way to keep the good bacteria in your gut healthy, says a dietitian and researcher.
Biochemical 'On-Switch' Could Solve Protein Purification Challenge
Oct 20, 2009 |
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(PhysOrg.com) -- Drugs based on engineered proteins represent a new frontier for pharmaceutical makers. Even after they discover a protein that may form the basis of the next wonder drug, however, they have ...
Genomes of Two Popular Research Strains of E. coli Sequenced
Oct 20, 2009 |
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(PhysOrg.com) -- An international team of researchers from the United States, Korea, and France has sequenced and analyzed the genomes of two important laboratory strains of E. coli bacteria, one used to study ...
Research for Organic Farming - Soya Thrives on Nitrogen From the Air
Oct 20, 2009 |
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For the first time, the capacity of soya plants to absorb nitrogen from the air has been precisely determined in dry areas of Eastern Austria. The primary aim of this project, backed by the FWF Austrian Science ...
Largest turtle-linked salmonella outbreak detailed
Oct 19, 2009 |
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(AP) -- Two girls who swam with pet turtles in a backyard pool were among 107 people sickened in the largest salmonella outbreak blamed on turtles nationwide, researchers report.
Time in a bottle: Scientists watch evolution unfold
Oct 18, 2009 |
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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 ...
Bacterium with grabber arms stops intruders
Oct 16, 2009 |
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Bacteria in drinks such as Vifit stop pathogens by using grabber-like arms to cling onto intestinal walls. This discovery is made by a group of Finnish, Belgium and Dutch researchers, under the coordination of Prof. Willem ...
