Selenite in the environment is extremely biotoxic, thus, the biotransformation of selenite into selenium nanoparticles (SeNPs) by microorganisms is gaining increasing interest. However, the relatively low selenite tolerance and slow processing by known microorganisms limit its application. In this study, a highly selenite-resistant strain (up to 800 mM) was isolated from coalmine soil and identified as Providencia rettgeri HF16. Remarkably, 5 mM selenite was entirely transformed by this strain within 24 h, and SeNPs were detected as early as 2 h of incubation, which is a more rapid conversion than that described for other microorganisms. The SeNPs were spherical in shape with diameters ranging from 120 nm to 295 nm, depending on the incubation time. Moreover, in vitro selenite-reduction activity was detected in the cytoplasmic protein fraction with NADPH or NADH serving as electron donors. Proteomics analysis and key enzyme activity tests revealed the presence of a sulfite reductase-mediated selenite reduction pathway. To our knowledge, this is the first report to identify the involvement of sulfite reductase in selenite reduction under physiological conditions. P. rettgeri HF16 could be a suitable and robust biocatalyst for the bioremediation of selenite, and would accelerate the efficient and economical synthesis of selenium nanoparticles.

环境中的亚硒酸盐具有极强的生物毒性，因此，微生物将亚硒酸盐生物转化为硒纳米颗粒（SeNPs）的兴趣日益增加。然而，相对较低的亚硒酸盐耐受性和已知微生物的缓慢加工限制了其应用。在这项研究中，从煤矿土壤中分离出了高度抗亚硒酸盐的菌株（最高达800 mM），被鉴定为Providencia rettgeriHF16。值得注意的是，该菌株在24小时内完全转化了5 mM的亚硒酸盐，最早在孵育2小时后就检测到SeNPs，这比其他微生物描述的转化更快。SeNP呈球形，其直径取决于孵育时间，直径范围为120 nm至295 nm。此外，以NADPH或NADH作为电子供体，在细胞质蛋白级分中检测到体外亚硒酸盐还原活性。蛋白质组学分析和关键的酶活性测试揭示了亚硫酸盐还原酶介导的亚硒酸盐还原途径的存在。据我们所知，这是首次鉴定在生理条件下亚硫酸还原酶参与亚硒酸盐还原过程的报告。瑞格斯体育 HF16可能是用于亚硒酸盐生物修复的合适且坚固的生物催化剂，并且将加速硒纳米颗粒的高效经济合成。