Anaerobic biotransformation of roxarsone and related N-substituted phenylarsonic acids

Environmental Science & Technology
By: , and 

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Abstract

Large quantities of arsenic are introduced into the environment through land application of poultry litter containing the organoarsenical feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid). The objective of this study was to evaluate the bioconversion of roxarsone and related N-substituted phenylarsonic acid derivatives under anaerobic conditions. The results demonstrate that roxarsone is rapidly transformed in the absence of oxygen to the corresponding aromatic amine, 4-hydroxy-3-aminophenylarsonic acid (HAPA). The formation of HAPA is attributable to the facile reduction of the nitro group. Electron-donating substrates, such as hydrogen gas, glucose, and lactate, stimulated the rate of nitro group reduction, indicating a microbial role. During long-term incubations, HAPA and the closely related 4-aminophenylarsonic acid (4-APA) were slowly biologically eliminated by up to 99% under methanogenic and sulfate-reducing conditions, whereas little or no removal occurred in heat-killed inoculum controls. Arsenite and, to a lesser extent, arsenate were observed as products of the degradation. Freely soluble forms of the inorganic arsenical species accounted for 19-28% of the amino-substituted phenylarsonic acids removed. This constitutes the first report of a biologically catalyzed rupture of the phenylarsonic group under anaerobic conditions. ?? 2006 American Chemical Society.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Anaerobic biotransformation of roxarsone and related N-substituted phenylarsonic acids
Series title Environmental Science & Technology
DOI 10.1021/es051981o
Volume 40
Issue 9
Year Published 2006
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Environmental Science and Technology
First page 2951
Last page 2957