Zhu Wenjie, Chai Liyuan, Ma Zemin, Wang Yunyan, Xiao Haijuan, Zhao Kun
School of Metallurgical Science and Engineering, Central South University, Changsha, Hunan Province 410083, PR China.
Microbiol Res. 2008;163(6):616-23. doi: 10.1016/j.micres.2006.09.008.
Hexavalent chromium [Cr(VI)] is a widespread environmental contaminant. Achromobacter sp. strain Chi was a Cr(VI) reducing bacterium with high reduction performance. Cr(VI) reductase was just existing in the cells, but was not discharged into the surrounding medium. Cr(VI) reduction was carried out with resting cells of strain Ch1 under anaerobic conditions. Initial pH value and lactate (electron donor) concentration were found to influence the reduction rate of Cr(VI), and the optimal conditions were at pH 9.0 and supplemented with 40 mM of lactate. The reduction rate would be constant under established conditions approximately 12.5 micromol 10(9) cells(-1) min(-1), which was not affected by cell density and initial Cr(VI) concentration. The maximal reduction capacity of Achromobacter sp. strain Ch1 was 54.2 mM, while the cell density of reduction system was 3.64 x 10(9) cells ml(-1). Energy-dispersive X-ray (EDX) analysis showed that chromium was precipitated perhaps as the form of Cr(OH)3.
六价铬[Cr(VI)]是一种广泛存在的环境污染物。无色杆菌属Chi菌株是一种具有高还原性能的Cr(VI)还原菌。Cr(VI)还原酶仅存在于细胞内，并未释放到周围培养基中。在厌氧条件下，利用菌株Ch1的静息细胞进行Cr(VI)还原。发现初始pH值和乳酸盐（电子供体）浓度会影响Cr(VI)的还原速率，最佳条件是pH 9.0并补充40 mM乳酸盐。在既定条件下，还原速率约为12.5微摩尔10(9)个细胞(-1)分钟(-1)，且不受细胞密度和初始Cr(VI)浓度的影响。无色杆菌属Chi菌株的最大还原能力为54.2 mM，而还原系统的细胞密度为3.64 x 10(9)个细胞毫升(-1)。能量色散X射线(EDX)分析表明，铬可能以Cr(OH)3的形式沉淀。
