Chemolithotrophic bacteria

Although they have not been obtained in pure culture, chemolithotrophic anaerobic bacteria (anammox) that oxidize ammonia using nitrite as electron donor and CO2 as a source of carbon have been described. In addition, they can oxidize propionate to CO2 (Giiven et al. 2005) by a pathway that has not yet been resolved. 

Matin A (1978) Organic nutrition of chemolithotrophic bacteria. Annu Rev Microbiol 32 433-468. 

Arsenite is also an intermediate in the fungal biomethylation of arsenic (Bentley and Chasteen 2002) and oxidation to the less toxic arsenate can be accomplished by heterotrophic bacteria including Alcaligenes faecalis. Exceptionally, arsenite can serve as electron donor for chemolithotrophic growth of an organism designated NT-26 (Santini et al. 2000), and both selenate and arsenate can be involved in dissimilation reactions as alternative electron acceptors. 

Cork [283], Sublette [284], and others have identified a number of chemolithotrophic bacteria which oxidize elemental sulfur and use reduced or partially reduced sulfur compounds as an energy source, in the presence of various carbon sources (such as carbon dioxide or bicarbonate) and reduced nitrogen (e.g., ammonium ion). In the case of Cork et al. s work, the anaerobic photosynthetic bacterium Chlorobium thiosulfatophilum is used to convert sulfides to sulfate. The economics of this process was not favorable due to the requirement of light for the growth of the bacterium. 

Sublette [285] describes a process for desulfurizing sour natural gas using another commonly known chemolithotrophic microorganism, the aerobic bacterium T. denitrifi-cans. This patent describes a process wherein bacteria of the Thiobacillus genus convert sulfides to sulfates under aerobic conditions. Sublette defined the ideal characteristics of a suitable microorganism for the oxidative H2S removal from gaseous streams as ... 

Microbial prodnction and consnmption of hydrogen by chemolithotrophic bacteria... 

Kelly DP. 1990. Energetics of chemolithotrophs. In Krulwich TA, editor. Volume 12, The bacteria. New York Academic Press, p 479-503. 

Kelly DP. 1999. Thermodynamic aspects of energy conservation by chemolithotrophic sulfur bacteria in relation to the sulfur oxidation pathways. Arch Microbiol 171 219-29. 

Peck HD. 1968. Energy-coupling mechanisms in chemolithotrophic bacteria. Ann Rev Microbiol 22 489-518. 

Yurkova NA, Lyalikova NN. 1991. New vanadate-reducing facultative chemolithotrophic bacteria. Microbiology 59 672-7. 

To return to the chemolithotrophs, there are species of sulfur bacteria that obtain energy from the oxidation of various stales of sulfur... 

Aerobic, chemolithotrophic bacteria. Colorless sulfur bacteria Thiobacillus iron or manganese-oxidizing bacteria, magnetotactic bacteria nitrifying bacteria Nitrobacter, Nitrosomonas... 

Bacteria 2. See also Specific genus and species acetic acid 8 aerobes 10 anaerobic 8 autotrophic 8 binding to cells 186 branched fatty acids of 381 chemoheterotrophic 7,8 chemolithotrophic 7 classification of 6-8 coats 431 composition of 31 electron micrograph of 4 flagella 6... 

Chemoheterotrophic bacteria 8 Chemolithotrophic bacteria 7 Chemoprevention 575 Chemoreceptors 562s bacterial 561—563 Chemostat 470 Chemotaxis... 

Some bacteria obtain all of their energy from inorganic reactions. These chemolithotrophs usually have a metabolism that is similar to that of hetero-trophic organisms, but they also have the capacity to obtain all of their energy from an inorganic reaction. 

Chemolithotrophic organisms often grow slowly, making study of their metabolism difficult.310 Nevertheless, these bacteria usually use electron transport chains similar to those of mitochondria. ATP is formed by oxidative phosphorylation, the amount formed per electron pair depending upon the number of proton-pumping sites in the chain. This, in turn, depends upon the electrode potentials of the reactions involved. For example, H2, when oxidized by 02, leads to passage of electrons through the entire electron transport chain with synthesis of 3 molecules of ATP per electron pair. On the other hand, oxidation by 02 of nitrite, for which E° (pH 7) = +0.42 V, can make use only of the site III part of the chain. Not only is the yield of ATP less than in the oxidation of H2 but also there is another problem. Whereas reduced pyridine... 

Chemolithotrophs obtain their energy from the oxidation of inorganic compounds such as hydrogen sulfide (H2S), hydrogen gas (H2), nitrite (NOj), ammonia (NH3), and ferrous iron (Fe2+). Chemolithotrophy is restricted to bacteria and is not found in higher forms of life. Chemolithotrophic bacteria are widespread in soil and water, and they benefit from the inorganic energy sources available in these habitats. 

The aerobic utilization of H2 is performed by facultatively chemolithotrophic hydrogen bacteria according to the following reaction ... 

Nitrification seems limited to a number of autotrophic bacteria. The dominant genus that is capable of oxidizing ammonia to nitrite in soils is Nitmsomonas, and the dominant genus capable of oxidizing nitrite to nitrate is Nitrobacter. Normally, the two processes are closely connected and nitrite accumulation does not occur. Nitrifying bacteria are chemolithotrophs that utilize the energy derived from nitrification to assimilate C02. 

Only a few compounds can serve as electron donors for sulfate reduction. The most common are pyruvate, lactate, and molecular hydrogen. Sulfate reduction is inhibited by oxygen, nitrate, or ferric ions and its rate is carbon-limited. Some bacteria are facultative chemolithotrophs as they can mixotroph-ically grow on acetate, C02, and H2. 

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