Methanogens -- oxygen producing bacteria

http://en.wikipedia.org/wiki/Methanogen

Methanogens are archaea that produce methane as a metabolic byproduct in anoxic conditions. They are common in wetlands, where they are responsible for marsh gas, and in the guts of animals such as ruminants and humans, where they are responsible for the methane content of flatulence.[1] In marine sediments biomethanation is generally confined to where sulfates are depleted, below the top layers.[2] Others are extremophiles, found in environments such as hot springs and submarine hydrothermal vents as well as in the "solid" rock of the Earth's crust, kilometers below the surface.

Methanogens play the vital ecological role in anaerobic environments of removing excess hydrogen and fermentation products that have been produced by other forms of anaerobic respiration. Methanogens typically thrive in environments in which all other electron acceptors (such as oxygen, nitrate, sulfate, and trivalent iron) have been depleted. In the deep rock they obtain their hydrogen from the thermal and radioactive breakdown of water.

Closely related to the methanogens are the anaerobic methane oxidizers, which utilize methane as a substrate in conjunction with the reduction of sulfate and nitrate.[10] Most methanogens are autotrophic producers, but those which oxidize CH3COO- are classed as chemoheterotrophs instead.


http://www.canada.com/Technology/Thank+oxygen+producing+bacteria+your+existence/1478323/story.html

oxygen-producing microbes, which transformed the oceans and the atmosphere and fuelled evolution of creatures that eventually crawled out of the sea, a Canadian-led team reports Thursday in the journal Nature.

"If the oxygen-producing bacteria had never taken over, we wouldn't be here right now," says lead author Kurt Konhauser, a geomicrobiologist at the University of Alberta.

The nickel-poor waters would, however, have been very hospitable to oxygen-producing microbes. And they soon took over as the dominant microbes, pumping oxygen into the oceans and air.

Marine scientist Mak Saito, of the Woods Hole Oceanographic Institution, describes the findings as both "exciting" and "sobering." It suggests "a single geological change can starve a major oceanic microbial community and thereby change the trajectory of life on Earth," Saito notes in a Nature commentary.

As the methanogen microbes died off, there would have been a big drop in atmospheric levels of methane gas, a potent greenhouse gas. This could have cooled the atmosphere, triggering the glaciation.

http://www.space.com/searchforlife/mars_conditions_020819.html
Kral led the experiment and presented it to colleagues during a bioastronomy conference in Australia last month.

"Our goal is first to get the organisms to grow well, then systematically experiment with conditions found on Mars," Kral said last week.

Mars' atmosphere contains large amounts of carbon dioxide with almost no oxygen. Assuming that hydrogen and some water are present under the surface, the basic requirements for methanogen growth are met on Mars. And even if hydrogen is not present, carbon monoxide is, and some methanogens can use this instead of hydrogen.

Since methane is a "greenhouse gas" that traps heat near a planets surface, methanogens could theoretically be used to raise Mars surface temperature, eventually "terraforming" the planet so that it could support life and provide a potential refuge for humanity.

http://zipcodezoo.com/Key/Archaea/Archaea_Kingdom.asp
Achaea kingdom, consists of crenarchaeota, nanoarchaeota, euryarchaeota
- single-celled microorganisms
- prokaryotes - have no cell nucleus or any other organelles within their cells
- Classifying the Archaea is still difficult, since the vast majority of these organisms have never been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from the environment.
- Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes: notably the enzymes involved in transcription and translation. Other aspects of archaean biochemistry are unique, such as their reliance on ether lipids in their cell membranes. The archaea exploit a much greater variety of sources of energy than eukaryotes: ranging from familiar organic compounds such as sugars, to using ammonia, metal ions or even hydrogen gas as nutrients. Salt-tolerant archaea (the Halobacteria) use sunlight as a source of energy, and other species of archaea fix carbon; however, unlike plants and cyanobacteria, no species of archaea is known to do both. Archaea reproduce asexually and divide by binary fission, fragmentation, or budding; in contrast to bacteria and eukaryotes, no species of archaea are known that form spores.
- archaea in plankton may be one of the most abundant groups of organisms on the planet
- One example are the methanogenic archaea that inhabit the gut of humans and ruminants, where they are present in vast numbers and aid in the digestion of food. Archaea have some importance in technology, with methanogens used to produce biogas and as part of sewage treatment, and enzymes from extremophile archaea that can resist high temperatures and organic solvents are exploited in biotechnology.