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Category: Environmental Microbiology
Arsenate-Respiring Bacteria, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555815882/9781555813796_Chap99-1.gif /docserver/preview/fulltext/10.1128/9781555815882/9781555813796_Chap99-2.gifAbstract:
This chapter highlights the various approaches and techniques that others have used to investigate the geomicrobiology of arsenate respiration in subsurface and aqueous environments. This includes the discussion of classical microbiological techniques (e.g, enrichment culture and pure strain studies), environmental DNA methods, and culture-dependent microcosm studies. The overall goal is to provide investigators with a concise overview of the tools used to better understand the biological mechanisms influencing the arsenic geochemical cycle. To date most arsenate-respiring microbes have been isolated as heterotrophs. To investigate how iron influences the arsenic geochemical cycle, many studies have used synthetic hydrous ferric oxide (HFO) as an adsorbant for either As(V) or As(III). This HFO-As mineral is then used in batch or flowthrough experiments with iron and/or arsenate reducers to characterize how microbes affect the mineralogy and mobilization of arsenic. The results of any sediment microcosm study should be interpreted with caution, especially when extrapolating to generalizations about what occurs in the environment. Manipulation of oxygenation may also provide useful information regarding the types of respiration that contribute to arsenic transformations. The substrate in the column can be sampled at the end of an experiment and analyzed for mineralogical transformations, changes in cell densities and spatial variations, and also for molecular markers such as 16S rRNA gene if natural sediments are used.
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Biochemistry influencing arsenic redox transformations and geochemical cycling of arsenic. The heavier arrows indicate the flow of electrons (either oxidation or reduction) to and from arsenic and specific proteins controlling the transformation. AroA, arsenite oxidase; ArrA, arsenate respiratory reductase.
Biochemical models for arsenic reduction or oxidation. The models show arsenate respiratory reduction by ArrA and arsenate reduction by ArsC coupled to arsenite detoxification through other Ars proteins.
List of known arsenate-respiring strains, their origins of isolation, and supporting references