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Investigation of Cr(VI) reduction potential and mechanism by Caldicellulosiruptor saccharolyticus under glucose fermentation condition
Journal of Hazardous Materials ( IF 13.6 ) Pub Date : 2017-10-29 , DOI: 10.1016/j.jhazmat.2017.10.059
Ya-Nan Bai , Yong-Ze Lu , Nan Shen , Tai-Chu Lau , Raymond Jianxiong Zeng

This study examined the microbial reduction of hexavalent chromium [Cr(VI)] by an extremely thermophilic bacterium, Caldicellulosiruptor saccharolyticus, under glucose fermentation conditions at 70 °C. Experimentation with different initial Cr(VI) concentrations confirmed that C. saccharolyticus had the ability to reduce Cr(VI) and immobilize Cr(III). At a concentration of 40 mg/L, Cr(VI) was completely reduced within 12 h, and 97% of the reduction product Cr(III) precipitated on the cell surface. Cr(VI) reduction was accelerated by the addition of neutral red (NR, an electron mediator), resulting in the reduction time shortened to 1 h. The addition of CuCl2, a Ni-Fe hydrogenase inhibitor, also enhanced Cr(VI) reduction. Additionally, analysis of the relationship between Cr(VI) reduction and glucose fermentation suggested that different electron sources acted during CuCl2 and NR conditions. Hydrogen served as an electron donor under normal fermentation and NR conditions with the catalysis of Ni-Fe hydrogenase. However, when the activity of Ni-Fe hydrogenase was inhibited by CuCl2, C. saccharolyticus directly used reduction equivalents during glucose fermentation for intracellular Cr(VI) reduction. Therefore, our findings demonstrated high Cr(VI) reduction ability and different electron transfer pathways during Cr(VI) reduction by C. saccharolyticus.

中文翻译:

葡萄糖发酵条件下蔗糖分解纤维素还原Cr(VI)的潜力及其机理的研究

这项研究研究了在70°C葡萄糖发酵条件下,一种极端嗜热细菌Caldicellulosiruptor saccharolyticus对六价铬[Cr(VI)]的微生物还原作用。用不同的初始Cr(VI)浓度进行的实验证实,解糖梭菌具有还原Cr(VI)和固定Cr(III)的能力。在40 mg / L的浓度下,Cr(VI)在12小时内被完全还原,还原产物Cr(III)的97%沉淀在细胞表面。Cr(VI)的还原通过添加中性红(NR,一种电子介体)而加速,导致还原时间缩短至1小时。添加CuCl 2Ni-Fe氢化酶抑制剂也增强了Cr(VI)的还原。此外,对Cr(VI)还原与葡萄糖发酵之间关系的分析表明,在CuCl 2和NR条件下,不同的电子源起作用。氢气在正常发酵和NR条件下通过Ni-Fe氢化酶的催化作用作为电子供体。然而,当镍-铁氢化酶的活性通过抑制的CuCl 2C. saccharolyticus葡萄糖发酵为细胞内的Cr(VI)还原期间直接使用还原当量。因此,我们的发现证明了高的Cr(VI)还原能力和糖酵解衣藻(Cr。saccharolyticus)还原Cr(VI)期间的不同电子传递途径。
更新日期:2017-10-30
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