Microbial transformation of arsenic and the characterization of Clostridium sp. strain OhILAs.

摘要

The impact of electron donor (acetate, pyruvate, lactate, formate, and hydrogen) and arsenate concentration (1, 5, 10, and 20 mM) on microbial arsenate reduction in freshwater sediments from the Ohio River, Pittsburgh PA was investigated. Hydrogen (with acetate as the carbon source) appeared to be the best electron donor and 5 mM sodium arsenate the most effective for both growth and orpiment (As2S3) production. A mesophilic, spore-forming, motile, low-mole %GC Gram-positive bacterium was isolated from Ohio River sediments on medium with 20 mM lactate and 10 mM arsenate. Although pH 8 was optimal for growth, 16S rRNA gene sequence analysis indicated that this species is most closely related to Alkaliphilus species, (A. crotonoxidans 95%, A. auruminator 95%, A. metaliredigenes, 94%). A strict anaerobic this species can ferment fructose and lactate and respire arsenate and thiosulfate. This bacterium is unique in that it can tolerate high arsenate concentrations (>40 mM) and readily degrades the organoarsenical roxarsone.