Shewanella oneidensis MR-1对Cr(VI)的还原及其影响因素

在实验室纯培养条件下，探讨厌氧体系中Shewanella oneidensis MR-1对Cr（VI）的还原能力，采用扫描电镜（SEM）-能谱（EDS）、X射线光电子能谱（XPS）等方法进行表征.结果表明，S.oneidensis MR-1介导下不同浓度Cr（VI）的生物转化与微生物对铬的耐受特性密切相关，低浓度Cr（VI）对其生长影响不大，高浓度时细菌生长则受到抑制，进而抑制Cr（VI）的还原率；菌株对Cr（VI）的还原作用随着接种菌悬液量的增加而增强；菌株最适生长pH值为中性，弱碱性环境比酸性环境更有利于菌株对Cr（VI）的还原；增加Fe（Ⅲ）的量会加快Cr（VI）完全还原的速率.通过SEM-EDS和XPS分析，在对Cr（VI）进行处理5d后，菌体表面有Cr（VI）和Cr（Ⅲ）两种形态存在，证实S.oneidensis MR-1在对Cr（VI）进行还原的同时也伴有少量的吸附作用.微生物还原为环境中Cr（VI）的去除以及解毒提供了一种有效的方法.

Reduction of Cr (VI) by Shewanella oneidensis MR-1 and its influencing factors

The ability of Shewanella oneidensis MR-1 to reduce Cr (VI) was investigated by pure culture under anaerobic condition in laboratory. The characterics of Cr (VI) reduction by S. oneidensis MR-1 was studied by scanning electron microscopy (SEM) equipped with an energy dispersive spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The results showed that the bioreduction of Cr (VI) at different initial concentrations was closely related to the tolerance of bacterial strains to chromium. Cr (VI) at low concentration had little effect on the strains growth. Cell growth was inhibited at high Cr (VI) concentration, thereby inhibiting the reduction of Cr (VI). The reduction of Cr (VI) increased with increasing the amount of strains inoculum. The optimum pH of the strains growth was neutral, and the weakly alkaline environment was more conducive to the Cr (VI) reduction than the acidic environment. The increasing amount of Fe (Ⅲ) accelerated the rate at which Cr (VI) was completely reduced. The results of SEM-EDS and XPS analysis showed that Cr (VI) and Cr (Ⅲ) existed on the surface of cells after treatment with Cr (VI) for 5days, which confirmed that Cr (VI) reduction by S. oneidensis MR-1was at the same time also accompanied by a small amount of Cr (VI) adsorption. Microbial reduction provides an effective method for the removal and detoxification of Cr (VI) in the environment.