Biovolatilisation of metal(loid)s by microorganisms

Michalke, Klaus; Hensel, Reinhard

doi:10.1007/978-3-662-09135-7_7

Cited by 4 publications

(1 citation statement)

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“…Biological production of volatile As compounds is considered to be an important part in the global As biogeochemical cycling (Michalke and Hensel, 2004). Bacteria, fungi, and alga can convert inorganic As into volatile compounds for As detoxification (Qin et al, , 2009Urík et al, 2007).…”

Section: Discussionmentioning

confidence: 99%

Biotransformation and Volatilization of Arsenic by Three Photosynthetic Cyanobacteria

Yin¹,

Chen²,

Qin³

et al. 2011

Plant Physiol.

175

145

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Arsenic (As) is a pervasive and ubiquitous environmental toxin that has created worldwide human health problems. However, there are few studies about how organisms detoxify As. Cyanobacteria are capable of both photolithotrophic growth in the light and heterotrophic growth in the dark and are ubiquitous in soils, aquatic systems, and wetlands. In this study, we investigated As biotransformation in three cyanobacterial species (Microcystis sp. PCC7806, Nostoc sp. PCC7120, and Synechocystis sp. PCC6803). Each accumulated large amounts of As, up to 0.39 g kg 21 dry weight, 0.45 g kg 21 dry weight, and 0.38 g kg 21 dry weight when treated with 100 mM sodium arsenite for 14 d, respectively. Inorganic arsenate and arsenite were the predominant species, with arsenate making up .80% of total As; methylated arsenicals were detected following exposure to higher As concentrations. When treated with arsenate for 6 weeks, cells of each cyanobacterium produced volatile arsenicals. The genes encoding the As(III) S-adenosylmethionine methyltransferase (ArsM) were cloned from these three cyanobacteria. When expressed in an As-hypersensitive strain of Escherichia coli, each conferred resistance to arsenite. Two of the ArsM homologs (SsArsM from Synechocystis sp. PCC6803 and NsArsM from Nostoc sp. PCC7120) were purified and were shown to methylate arsenite in vitro with trimethylarsine as the end product. Given that ArsM homologs are widespread in cyanobacteria, we propose that they play an important role in As biogeochemistry.

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Section: Discussionmentioning

confidence: 99%