Chromium( vi ) contaminated sites have been targeted for studying highly chromate-resistant bacteria. From a total of 23 Cr( vi )-resistant bacteria isolated on Luria-Bertani agar medium supplemented with K 2 CrO 4 (1,500 μg/mL), only one strain UT8 ( Staphylococcus simulans ) was able to tolerate high concentration of chromate, i.e., up to 200 mg/mL in agar medium from tannery effluent. In acetate minimal medium (AMM), it showed maximum tolerance of up to 2,500 μg/mL. Cr( vi ) removal potential was 94.6% after 24 h (K 2 CrO 4 1,500 μg/mL). Parametric conditions were optimized in AMM to attain maximum chromate removal. Exopolysaccharides extracted from bacterial cells exposed to chromate exhibited major absorption shifts from 2,500 to 500 cm −1 revealed by Fourier transform infrared spectroscopy. Energy-disperse X-ray spectroscopy further confirmed the adsorption of oxyanions to the bacterial cells. Surface topography of the Cr( vi ) treated cells showed transformation into concave shape by scanning electron microscopy. The presence of resistance genes, i.e., chromate reductase ( chrR ) and class I integrase ( intI1 ), further confirmed tolerance toward chromate. Microarray data analysis of transcriptional gene expression suggested upregulation of cys gene cluster under chromate exposure. Concisely, the present investigations revealed the potential of S. simulans to be an effective candidate for chromate reclamation of wastewater. Graphical abstract Chromate-resistant bacterium UT8 was isolated from tannery effluent. The cultural conditions for strain UT8 were optimized for maximum chromate removal and exopolymer production. SEM-EDS analysis of strain UT8 revealed variations under Cr( vi ) stress related to nonstress. The FTIR analysis of exopolymer under chromate stress indicated vibrational shifts for metal ion chelation.

中文翻译：

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高度耐Cr（vi）的葡萄球菌模拟物协助从制革厂废水中抽出铬酸盐

铬（vi）污染的地点已被用于研究高度抗铬酸盐的细菌。从补充有K 2 CrO 4（1,500μg/ mL）的Luria-Bertani琼脂培养基上分离出的总共23种抗Cr（vi）细菌中，只有一种菌株UT8（Staphylococcus simulans）能够耐受高浓度的铬酸盐，即在制革厂废水中的琼脂培养基中最高可达200​​ mg / mL。在醋酸盐基本培养基（AMM）中，它显示的最大耐受量高达2500μg/ mL。24小时后（K 2 CrO 4 1,500μg/ mL），Cr（vi）的去除潜力为94.6％。在AMM中对参数条件进行了优化，以实现最大的铬酸盐去除率。从暴露于铬酸盐的细菌细胞中提取的胞外多糖表现出从2500到500 cm -1的主要吸收位移，这是通过傅立叶变换红外光谱法揭示的。能量分散X射线光谱进一步证实了氧阴离子被细菌细胞吸收。Cr（vi）处理过的细胞的表面形貌通过扫描电子显微镜观察显示转化为凹形。抗性基因的存在，即铬酸还原酶（chrR）和I类整合酶（intI1）的存在进一步证实了对铬酸的耐受性。转录基因表达的微阵列数据分析表明在铬酸盐暴露下cys基因簇的上调。简而言之，本研究表明，拟链霉菌有可能成为废水铬酸盐回收的有效候选者。从制革厂废水中分离出图形抽象的抗铬酸盐细菌UT8。针对菌株UT8的培养条件进行了优化，以最大程度地去除铬酸盐和生成外聚物。UT8应变的SEM-EDS分析揭示了在Cr（vi）应力下与非应力有关的变化。在铬酸盐应力下，外聚合物的FTIR分析表明金属离子螯合的振动位移。