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.

中文翻译：

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无色杆菌属细菌细胞厌氧还原六价铬。应变Ch1。

六价铬[Cr（VI）]是一种广泛的环境污染物。无色杆菌 Chi菌株是具有高还原性能的Cr（VI）还原细菌。Cr（VI）还原酶仅存在于细胞中，但没有排放到周围的培养基中。Cr（VI）还原是在厌氧条件下用菌株Ch1的静止细胞进行的。发现初始pH值和乳酸（电子供体）的浓度会影响Cr（VI）的还原速率，最佳条件是pH 9.0并补充40 mM乳酸。在确定的条件下，还原速率将保持恒定，约为12.5 micromol 10（9）cells（-1）min（-1），不受细胞密度和初始Cr（VI）浓度的影响。无色杆菌最大还原能力。Ch1菌株为54.2 mM，而还原系统的细胞密度为3.64 x 10（9）个细胞ml（-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。