中文摘要：

利用一株新分离的Cr（Ⅵ）还原菌Leucobacter spp．Ch1进行高浓度Cr（Ⅵ）还原的研究。发现生长于LuriaBroth培养基中的Leucobacter spp．Ch1最大能还原1800mg／L Cr（Ⅵ），而休眠Leucobacter spp．Ch1细胞悬液可以完全还原2100mg／L Cr（Ⅵ）。扫描电镜观察到还原Cr（Ⅵ）后的细菌末端黏附大团反应产物，电子顺磁共振分析确定产物的成分为Cr（Ⅲ）。在分批加Cr（Ⅵ）还原实验中，休眠Leucobacter spp．Ch1细胞悬液在1060min内还原了2368mg／LCr（Ⅵ），重新加入的乳酸钠可以再次启动Cr（Ⅵ）的生物还原。结果表明，乳酸钠的存在是Leucobacter spp．Ch1还原Cr（Ⅵ）的必要条件，推测该物质在反应中起电子供体的作用。

英文摘要：

A novel chromate reducing bacteria Leucobacter spp. Ch1 was used to reduce high concentrations of Cr（Ⅵ ）. While the growing bacteria cultured in the Luria Broth media, the maximum concentration of Cr（ Ⅵ ） reduced entirely to 1 800 mg/L and 2 100 mg/L of Cr（ Ⅵ） and was removed in resting cells suspensions. The shape of Leucobacter spp. Chl after chromate reduction was observed by scanning electron microscopy and amorphous conglomera- tion was found adhering on the terminal of Ch1 cells. The major element of the reduction product was determined as Cr（Ⅲ） with electron paramagnetic resonance （EPR） spectrometry. In chromate reduction of multi-addition, 2 368 mg/L of Cr（ Ⅵ ） was reduced by cell suspension within 1 010 rain. The bacterial reduction of Cr（ Ⅵ ） could be restarted by sodium lactate supplemented again. Results indicated that sodium lactate was absolutely necessary need for the chromate reduction of Leucobacter spp. Chl and should act as an electron donor in chromate reduction to supply elec- trons.