Abstract Carcinogenic effects of arsenic through consumption of contaminated water are an alarming threat and there is an emergent need to reduce extremely high levels of toxic arsenic from environment. Bacterial biofilms produce polyanionic extracellular polymeric substance (EPS) that is considered an excellent biosorbent material for the remediation of toxic metals and metalloids. This study was aimed to investigate the role of bacterial EPS in arsenic bioremediation. EPS was extracted from biofilm forming and arsenic reducer bacterial strains that were isolated from industrial waste water and characterized biochemically. Fourier transform infrared spectroscopy was also performed to study functional groups. Both Exiguobacterium profundum PT2 and Ochrobactrum ciceri SW1 exhibited enhanced EPS production in the presence of arsenic. Arsenic stress increased protein and carbohydrate contents in the EPS of both bacterial strains as indicated by the peaks of 1363 to 1613 and 1035 to 1218 cm−1 wavenumbers, respectively to cope with arsenic present in the surroundings. Shifting of peaks in As5+ treated samples from 1363 to 1379, 847 to 800 and 1211 to 1134 cm−1 demonstrated the involvement of proteins, carbohydrates and phosphates in the sequestration of arsenic. Scanning electron microscopic examination of EPS revealed structural alterations such as the presence of closely embedded large clumps with interstitial spaces between stacked layers of the EPS of E. profundum PT2 treated with As5+ displayed the enhanced polysaccharide content and arsenic sorption. Therefore, increased production of bacterial EPS with large number of polyanionic functional groups on its surface having tendency to sequester arsenic through electrostatic or covalent interactions presented EPS an excellent biosorbent material for arsenic bioremediation.

中文翻译：

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细菌胞外聚合物作为砷生物修复生物吸附材料的潜在作用

摘要 食用受污染的水所产生的砷致癌作用是一个令人担忧的威胁，迫切需要减少环境中极高水平的有毒砷。细菌生物膜产生聚阴离子细胞外聚合物 (EPS)，它被认为是一种极好的生物吸附材料，用于修复有毒金属和类金属。本研究旨在探讨细菌 EPS 在砷生物修复中的作用。EPS 是从工业废水中分离出的生物膜形成和降砷细菌菌株中提取的，并进行了生化表征。还进行了傅里叶变换红外光谱来研究官能团。在存在砷的情况下，深部微小杆菌 PT2 和 Ochrobactrum ciceri SW1 均表现出增强的 EPS 产量。砷胁迫增加了两种细菌菌株 EPS 中蛋白质和碳水化合物的含量，分别由 1363 至 1613 和 1035 至 1218 cm-1 波数的峰值表明，以应对周围环境中存在的砷。As5+ 处理样品中的峰从 1363 到 1379、847 到 800 和 1211 到 1134 cm-1 的移动表明蛋白质、碳水化合物和磷酸盐参与了砷的螯合。EPS 的扫描电子显微镜检查揭示了结构改变，例如存在紧密嵌入的大团块，在用 As5+ 处理的深海大肠菌 PT2 的 EPS 堆叠层之间存在间隙空间，显示出增强的多糖含量和砷吸附。所以，