Arsenic occurs in natural waters as arsenate and arsenite anions and is generally considered to be toxic to biological systems (ToxFAQs: Arsenic). Sources of arsenic in the environment include volcanic activity, coal burning, metal smelting, and acid mine drainage. Organoarsenic compounds are also added to chicken feed as antibiotics.

Arsenate uptake typically occurs through phosphate transport systems, whereas arsenite is often acquired via aquaglyceroporins (reviewed by Rosen, 2002). No essential biological function for arsenic has been identified, but marine algae and invertebrates can incorporate arsenic into complex organic molecules such as arsenosugars and arsenobetaines (Kohlmeyer et al, 2002) and fungi and bacteria can produce volatile methylated arsenic compounds (reviewed by Bentley and Chasteen, 2002). Both microbial arsenate reduction and arsenite oxidation are well documented as detoxification mechanisms (reviewed by Mukhopadhyay et al, 2002). Additionally, some prokaryotes can use arsenate as a terminal electron acceptor during anaerobic growth and others can utilize arsenite as an electron donor to generate energy (reviewed by Oremland and Stoltz, 2003). In a Shewanella sp., respiratory arsenate reduction and detoxifying arsenate reduction were found to be mediated by separate systems (Saltikov and Newman, 2003).

For more information:

Search Medline for arsenic metabolism AND bacteria

Salmassi TM, et al. Oxidation of Arsenite by Agrobacterium albertimagni, AOL15, sp. nov., Isolated from Hot Creek, California. Geomicrobiology J. 2002;19:53-66.

Niggemyer A, Spring S, Stackebrandt E, Rosenzweig RF. Isolation and characterization of a novel As(V)-reducing bacterium: implications for arsenic mobilization and the genus Desulfitobacterium. Appl Environ Microbiol. 2001 Dec;67(12):5568-80.

Tamas MJ, Wysocki R. Mechanisms involved in metalloid transport and tolerance acquisition. Curr Genet. 2001;40:2-12.

 


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