Shewanella oneidensis MR-1-Induced Fe(III) Reduction Facilitates Roxarsone Transformation.
Although microbial activity and associated iron (oxy)hydroxides are known in general to affect the environmental dynamics of 4-hydroxy-3-nitrobenzenearsonic acid (roxarsone), the mechanistic understanding of the underlying biophysico-chemical processes remains unclear due to limited experimental information. We studied how Shewanella oneidensis MR-1 -a widely distributed metal-reducing bacterium, in the presence of dissolved Fe(III), affects roxarsone transformations and biogeochemical cycling in a model aqueous system. The results showed that the MR-1 strain was able to anaerobically use roxarsone as a terminal electron acceptor and to convert it to a single product, 3-amino-4-hydroxybenzene arsonic acid (AHBAA). The presence of Fe(III) stimulated roxarsone transformation via MR-1-induced Fe(III) reduction, whereby the resulting Fe(II) acted as an efficient reductant for roxarsone transformation. In addition, the subsequent secondary Fe(III)/Fe(II) mineralization created conditions for adsorption of organoarsenic compounds to the yielded precipitates and thereby led to arsenic immobilization. The study provided direct evidence of Shewanella oneidensis MR-1-induced direct and Fe(II)-associated roxarsone transformation. Quantitative estimations revealed a candidate mechanism for the early-stage environmental dynamics of roxarsone in nature, which is essential for understanding the environmental dynamics of roxarsone and successful risk assessment.
School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China.
Guowei
G
Chen
School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China.
Zhengchen
Z
Ke
School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China.
Tengfang
T
Liang
School of Civil and Hydraulic Engineering, Hefei University of Technology, Hefei 230009, China.
Li
L
Liu
Department of Soil and Water Sciences, China Agricultural University, Beijing 100193, China.
Gang
G
Wang
D001711:Biotransformation; D005290:Ferric Compounds / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D012406:Roxarsone / Q000378:metabolism*; D020592:Shewanella / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
D005290:Ferric Compounds; D012406:Roxarsone