Abstract：
Extracellular polymeric substances (EPS) have demonstrated significant benefits for reducing multivalent metal contamination. Using Achromobacter xylosoxidans BP1 isolated from a coal chemical site in China, this study elucidated the contribution of EPS production to Cr (VI) reduction and revealed its biological removal mechanism. BP1 grew at an optimum pH of 8 and the lowest inhibitory concentration of Cr(VI) was 300 mg/L. The spent medium completely removed Cr(VI), whereas resting cells were only able to remove 10.47 % and inactivated cells were nearly incapable of Cr(VI) removal. S-EPS and B-EPS reduced Cr(VI) by 98.59 % and 11.64 %, respectively. SEM-EDS analysis showed that the BP1 cells were stimulated to produce EPS under Cr stress. The XPS results showed that 29.63 % of Cr(VI) was enriched by intracellular bioaccumulation or biosorption and 70.37 % of Cr(VI) was reduced by extracellular enzymes to produce Cr(OH)3 and organic Cr(III) complexes. According to FTIR, EPS with -OH, COO-, and amide groups supplied binding sites and electrons for the reductive adsorption of Cr(VI). Genomic studies showed that BP1 primarily produces extracellular polysaccharides, metabolises sulphur and nitrogen, and reduces reactive oxygen species damage as a result of DNA repair proteases.
摘要：
胞外聚合物质(EPS)已显示出减少多价金属污染的显著益处。使用从中国煤化工场所分离出的木氧无色杆菌BP1，这项研究阐明了EPS产生对Cr（VI）还原的贡献，并揭示了其生物去除机理。BP1在最适pH为8时生长，Cr（VI）的最低抑制浓度为300mg/L。废培养基完全去除Cr(VI)，静息细胞只能去除10.47％，失活细胞几乎不能去除Cr（VI）。S-EPS和B-EPS降低Cr（VI）98.59％和11.64％，分别。SEM-EDS分析表明，在Cr胁迫下，BP1细胞被刺激产生EPS。XPS结果表明，通过细胞内生物富集或生物吸附富集了29.63％的Cr（VI），通过细胞外基质酶还原了70.37％的Cr（VI），产生了Cr（OH）3和有机Cr（III）复合物。根据FTIR，带有-OH的EPS,COO-,和酰胺基团为Cr（VI）的还原吸附提供了结合位点和电子。基因组研究表明，BP1主要产生胞外多糖，代谢硫和氮，并减少DNA修复蛋白酶导致的活性氧损伤。
