Jiangsu Key Laboratory for Organic Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
College of Ecology and Environment and Co-Innovation Center for the Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu 210037, China.
Sci Total Environ. 2024 Dec 1;954:176529. doi: 10.1016/j.scitotenv.2024.176529. Epub 2024 Sep 27.
The biogeochemical cycling of arsenic (As) is often intertwined with iron (Fe) and sulfur (S) cycles, wherein Fe(III)- and sulfate-reducing bacteria (SRB) play a crucial role. Here, we isolated strain DS-1, a strictly anaerobic Fe(III)- and sulfate-reducing bacterium, from As-contaminated paddy soil. Using 16S rRNA gene sequence analysis, strain DS-1 was identified as a member of the genus Desulfovibrio. Strain DS-1 utilized energy derived from ferrihydrite reduction to support its cellular growth. Under anoxic sulfate-reducing conditions, the presence of strain DS-1 significantly increased As mobilization compared to sulfate-free conditions. Mechanistically, SRB-produced sulfide reacts with Fe(III) to form FeS, which disrupts Fe(III) minerals, thereby enhancing As release. These findings highlight the critical role of redox disequilibrium in As mobilization and suggest that SRB-produced sulfide may permeate to the rice rhizosphere, increasing As mobilization through Fe(III) reduction.
砷（As）的生物地球化学循环通常与铁（Fe）和硫（S）循环交织在一起，其中三价铁还原菌（Fe(III)-reducing bacteria）和硫酸盐还原菌（SRB）起着至关重要的作用。在这里，我们从受 As 污染的稻田土壤中分离出一株严格厌氧的 Fe(III)-和硫酸盐还原菌，命名为 DS-1 株。通过 16S rRNA 基因序列分析，菌株 DS-1 被鉴定为脱硫弧菌属（Desulfovibrio）的一个成员。菌株 DS-1 利用来源于水铁矿还原的能量来支持其细胞生长。在缺氧硫酸盐还原条件下，与无硫酸盐条件相比，DS-1 菌株的存在显著增加了 As 的迁移。从机制上讲，SRB 产生的硫化物与 Fe(III)反应形成 FeS，破坏 Fe(III)矿物，从而促进 As 的释放。这些发现强调了氧化还原失衡在 As 迁移中的关键作用，并表明 SRB 产生的硫化物可能渗透到水稻根际，通过 Fe(III)还原增加 As 的迁移。
