Abstract：
The microbial reduction of selenite to elemental selenium nanoparticles (SeNPs) is thought to be an effective detoxification process of selenite for many bacteria. In this study, Metasolibacillus sp. ES129 and Oceanobacillus sp. ES111 with high selenite reduction efficiency or tolerance were selected for systematic and comparative studies on their performance in selenite removal and valuable SeNPs recovery. The kinetic monitoring of selenite reduction showed that the highest transformation efficiency of selenite to SeNPs was achieved at a concentration of 4.24 mM for ES129 and 4.88 mM for ES111. Ultramicroscopic analysis suggested that the SeNPs produced by ES111 and ES129 had been formed in cytoplasm and subsequently released to extracellular space through cell lysis process. Furthermore, the transcriptome analysis indicated that the expression of genes involved in bacillithiol biosynthesis, selenocompound metabolism and proline metabolism were significantly up-regulated during selenite reduction, suggesting that the transformation of selenite to Se0 may involve multiple pathways. Besides, the up-regulation of genes associated with nucleotide excision repair and antioxidation-related enzymes may enhance the tolerance of bacteria to selenite. Generally, the exploration of selenite reduction and tolerance mechanisms of the highly selenite-tolerant bacteria is of great significance for the effective utilization of microorganisms for environmental remediation.
摘要：
亚硒酸盐微生物还原成元素硒纳米颗粒（SeNP）被认为是亚硒酸盐对许多细菌的有效解毒过程。在这项研究中,变液杆菌。ES129和海洋芽孢杆菌。选择具有高亚硒酸盐还原效率或耐受性的ES111用于系统和比较研究其在亚硒酸盐去除和有价值的SeNPs回收中的性能。亚硒酸盐还原的动力学监测表明，在ES129的浓度为4.24mM和ES111的浓度为4.88mM时，亚硒酸盐向SNP的转化效率最高。超显微分析表明，ES111和ES129产生的SeNPs已在细胞质中形成，随后通过细胞裂解过程释放到细胞外空间。此外，转录组分析表明，参与杆菌锂醇生物合成的基因的表达，硒化合物代谢和脯氨酸代谢在亚硒酸盐还原过程中显著上调，这表明亚硒酸盐向Se0的转化可能涉及多种途径。此外,与核苷酸切除修复和抗氧化相关酶相关的基因的上调可能增强细菌对亚硒酸盐的耐受性。一般来说,探索高耐亚硒酸盐细菌的亚硒酸盐还原和耐受机制，对于有效利用微生物进行环境修复具有重要意义。
