The release of hexavalent chromium [Cr (VI)] into environments has resulted in many undesirable interactions with biological systems for its toxic potential and mutagenicity. Chromate reduction via chromium reductase (ChrR) is a key strategy for detoxifying Cr (VI) to trivalent species of no toxicity. In this study, ten bacterial isolates were isolated from heavily polluted soils, with a strain assigned as FACU, being the most efficient one able to reduce Cr (VI). FACU was identified as Escherichia coli based on morphological and 16S rRNA sequence analyses. Growth parameters and enzymatic actions of FACU were tested under different experimental conditions, in the presence of toxic chromium species. The E. coli FACU was able to reduce chromate at 100 μg/mL conceivably by reducing Cr (VI) into the less harmful Cr (III). Two distinctive optical spectroscopic techniques have been employed throughout the study. Laser-induced breakdown spectroscopy (LIBS) was utilized as qualitative analysis to demonstrate the presence of chromium with the distinctive spectral lines for bacteria such as Ca, Fe, and Na. While UV-visible spectroscopy was incorporated to confirm the reduction capabilities of E. coli after comparing Cr (III) spectrum to that of bacterial product spectrum and they were found to be identical. The chromate reductase specific activity was 361.33 μmol/L of Cr (VI) per min per mg protein. The FACU (EMCC 2289) 16S rRNA sequence and the ChrR-partially isolated gene were submitted to the DDBJ under acc. # numbers LC177419 and LC179020, respectively. The results support that FACU is a promising source of ChrR capable of bioremediation of toxic chromium species.

六价铬[Cr（VI）]释放到环境中已导致与生物系统发生许多不良相互作用，这是因为它具有潜在的毒性和致突变性。通过铬还原酶（ChrR）还原铬酸盐是将Cr（VI）解毒成无毒的三价物种的关键策略。在这项研究中，从重度污染的土壤中分离出十种细菌分离株，并将其命名为FACU，这是能够还原Cr（VI）的最有效菌株。根据形态学和16S rRNA序列分析，FACU被鉴定为大肠杆菌。在有毒铬物种存在的情况下，在不同的实验条件下测试了FACU的生长参数和酶促作用。该大肠杆菌FACU可以通过将Cr（VI）还原为危害较小的Cr（III）来减少100μg/ mL的铬酸盐。在整个研究过程中采用了两种独特的光谱技术。激光诱导击穿光谱法（LIBS）被用作定性分析，以证明铬的存在以及细菌诸如Ca，Fe和Na的独特光谱线。在将Cr（III）光谱与细菌产物光谱进行比较后，将紫外可见光谱法用于确认大肠杆菌的还原能力，发现它们是相同的。铬还原酶的比活性为每毫克蛋白每分钟361.33μmol/ L Cr（VI）。FACU（EMCC 2289）16S rRNA序列和ChrR将部分分离的基因按照acc。提交给DDBJ。＃分别为LC177419和LC179020。结果表明，FACU是有希望的ChrR来源，能够对有毒铬物种进行生物修复。