Английская Википедия:Acidithrix ferrooxidans
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Acidithrix ferrooxidans (A. ferrooxidans) is a heterotrophic, acidophilic and Gram-positive bacterium from the genus Acidithrix. The type strain of this species, A. ferrooxidans Py-F3, was isolated from an acidic stream draining from a copper mine in Wales.[1][2][3] This species grows in a variety of acidic environments such as streams, mines or geothermal sites.[1] Mine lakes with a redoxcline support growth with ferrous iron as the electron donor.[1][4] "A. ferrooxidans" grows rapidly in macroscopic streamer, producing greater cell densities than other streamer-forming microbes.[5] Use in a bioreactors to remediate mine waste has been proposed due to cell densities and rapid oxidation of ferrous iron oxidation in acidic mine drainage.[5] Exopolysaccharide production during metal substrate metabolism, such as iron oxidation helps to prevent cell encrustation by minerals.[4]
Isolates/Sequencing
Isolate Py-F3
Type strain Py-F3 was isolated from acidic, metal-rich mine waters in North Wales.[4] Py-3 can grow different metabolisms for potential growth substrates,[3] and can grow at a range of temperatures from 10 to 30 °C and pH from1.5–4.4.[3] Strain Py-F3 encodes multiple enzymes for carbon fixation, including RubisCO, but its carbon fixation activity has not been studied.[3] Genes encoding proteins for metabolic pathways utilizing sulfur, nitrogen, and iron were discovered in the genome.[3] The source of sulfur is sulfate, and it can use amino acids as a nitrogen source. This is unique requirement of isolate Py-F3, leaving it with an inability to grow in media unless complex substrates are added.[3] For pH homeostasis the urease genes could aid survival due to encoded the proton pumping activity.[3] Uptake of urea is documented in Py-F3 and allows for the intracellular production of urea, rather than taking it in to the cell.[3] This organism's peptidoglycan contains meso-diaminopimelic acid and with major fatty acid chains and a respiratory quinone.[3]
Isolate C25
Isolate C25 was recovered from particulate iron forming in a pelagic iron-rich redoxcline zone of a mine lake.[4] This isolate can both oxidize Fe(II) and reduce Fe(III) under micro-oxic conditions, and was suggested to contribute to the formation of particulate iron in the pelagic environment.[4] Growth did not occur at pH lower than that of Py-F3 (pH) of 2, while C25 had a higher pH tolerance.[4] The observation that C25 can both oxidize and reduce iron provides insights into how microbes cycle both iron and organic carbon under acidic conditions.[4] Fast rates of iron oxidation lead to the regeneration of ferric iron in the environment at a pH as low as 1.5.[6][5] Compared to Py-F3, C25 did not encode for the ribulose, but future studies will need to be done for a definitive answer.[4]
Application to Bioremediation
The strains grow using iron metabolism on Tryptic Soy Broth/Agar (TSA/TSB) at low pH, where bacterial colonies form with iron precipitates.[4][5] Lab conditions of 25 °C aerobically allowed for ferrous iron oxidation to occur in sterilized lake medium.[4] Researchers recognized the potential of utilizing "A. ferrooxidans" for a bioreactor through growth/adherence on solid surfaces.[5] Iron mines make an excellent growing condition and analogy for the bioreactor due to those similar surfaces.[5] Utilizing the bacteria can facilitate soluble iron removal from ferruginous water, and the iron (III) production contributes to sulfide minerals dissolving.[5]
References
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