湖南冷水江锡矿山尾矿库细菌富集群落与辉锑矿的相互作用及其群落演替

Interaction between Stibnite and Microbial Communities Enriched from Tailings at Xikuangshan Coupling with Bacterial Community Succession

为了从群落水平上探讨细菌对辉锑矿的溶解释放作用,从湖南锡矿山尾矿库尾矿渣中富集了细菌群落,开展了其与辉锑矿相互作用的实验研究.通过湿化学方法检测实验过程中pH和锑含量的变化、用16S rRNA高通量测序检测实验过程中细菌群落的变化,用X射线粉晶衍射仪(XRD)检测微生物与矿物相互作用后矿物相的变化,进而揭示群落水平上微生物与辉锑矿相互作用的机制及相互作用过程中细菌群落的演替.结果表明在好氧条件下细菌群落可以以乳酸钠为碳源进行异养生长,造成溶液pH的升高,进而导致辉锑矿的溶解.实验初期辉锑矿溶解释放的三价锑迅速被氧化成五价锑,但第9 d之后三价锑开始在溶液中积累,在实验结束时浓度比五价锑略高.溶液中五价锑的浓度在第12 d之前持续上升,之后下降,直至实验结束.溶液中锑含量的升高,对细菌群落进行了强烈的筛选作用.实验过程中细菌群落均以对As/Sb等多种重金属具有抗性的草螺菌属(Herbaspirillum)占绝对优势,但其相对丰度在第11 d之后有所下降.具有锑氧化能力的细菌类群如副球菌属(Paracoccus)、博斯氏菌属(Bosea)等在群落中的相对丰度较低,导致辉锑矿溶解释放出来的三价锑不能被完全氧化.XRD结果显示辉锑矿与细菌群落作用后生成了含有五价锑的锑酸钠,这与溶液中五价锑浓度的下降相吻合.该结果为进一步理解锡矿山自然环境中细菌群落对含锑矿物的溶解、锑的氧化、迁移和转化的影响提供了新的认识.

To better understand microbial dissolution and oxidation of stibnite at the community level,microbial communities were enriched from the tailings in the Xikuangshan tailings pond,Hunan Province,which were further used to study microbial interaction with stibnite.pH,total Sb,Sb(V),Sb(III)and SO42-were measured periodically.16S rRNA high-throughput sequencing and X-ray powder diffractometer(XRD)were exploited to detect compositions of microbial communities and mineral phases,respectively.The results show that microbial communities can grow with sodium lactate and increase the pH of the solution under aerobic condition,which facilitated the dissolution of stibnite.The concentration of Sb(V)accumulated in the solution due to the oxidation of the released Sb(III),with an decrease after the 12th day.The Sb(III)concentration in the solution increased after the 9th day and was a little bit higher than that of Sb(V)at the end of the experiments.The incomplete oxidation of Sb(III)may result from the low relative abundances of antimony-oxidizing bacteria such as Paracoccus and Bosea in the enriched culture.The variation of solution chemistry,particularly the Sb concentration,exerted strong selection on microbial communities.Microbial communities were dominated by Herbaspirillum sp.,with strong resistance to metals,such as and Sb.However their relative abundances decreased after 11 days’interaction potentially due to the accumulation of Sb in the system.Secondary Sb(V)-bearing mineral,sodium antimonite,was detected at the end of the experiments in the biotic systems,which matched well with the decrease of the concentration of Sb(V)in the solution.Our results further confirm the mechanism of microbial dissolution of stibnite followed by oxidation and transformation of minerals at the community level,which provides new insights of understanding the impact of microbial communities on the dissolution of Sb-bearing secondary minerals,oxidation,migration and formation of antimony in natural environments.