Key Laboratory of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2020 Dec;27(35):44205-44217. doi: 10.1007/s11356-020-10274-5. Epub 2020 Aug 5.
Microbes play an important role in the biotransformation of arsenic (As) speciation in various environments. Nevertheless, whether epiphytic bacteria that attached on submerged macrophytes have the potential to influence As speciation still remains unclear. In this study, sterile or nonsterile Myriophyllum verticillatum was cultured with arsenite (As(III)) or arsenate (As(V)) to investigate the impact of epiphytic bacterial community on As uptake, transformation, and efflux. Results showed that both sterile and nonsterile M. verticillatum did not display substantial As(III) oxidation, suggesting that neither M. verticillatum nor epiphytic bacterial community has the capacities of As(III) oxidation. However, sterile M. verticillatum exhibited capacity for As(V) reduction, and the presence of epiphytic bacterial community substantially enhanced the proportions of As(III) in the medium (from 39.91 to 98.44%), indicating that epiphytic bacterial community contributes significantly to As(V) reduction in the medium. The presence of epiphytic bacterial community elevated As accumulation (by up to 2.06-fold) in plants when exposed to As(V). Results also showed that epiphytic bacterial community contributed little to As(III) efflux. Quantitative PCR of As metabolism genes revealed the dominance of the respiratory As(V) reductase genes (arrA) in epiphytic bacterial community, which might play a significant role in As(V) reduction in aquatic environments. Phylogenetic analysis of the arrA genes revealed the widely distribution and diversity of As(V)-respiring bacteria. These results highlighted the substantial impact of the epiphytic bacterial community associated with submerged aquatic macrophytes on As biogeochemistry in wetland and water environments.
微生物在各种环境中砷形态的生物转化中发挥着重要作用。然而，附着在沉水植物上的附生细菌是否有可能影响砷形态仍不清楚。本研究采用无菌或非无菌的菹草培养亚砷酸盐（As(III)) 或砷酸盐 (As(V))，以研究附生细菌群落对砷吸收、转化和外排的影响。结果表明，无菌和非无菌菹草均未表现出大量的 As(III) 氧化，这表明菹草和附生细菌群落均不具有 As(III) 氧化能力。然而，无菌菹草表现出砷酸盐（As(V)) 还原能力，而附生细菌群落的存在显著提高了培养基中 As(III) 的比例（从 39.91%增加到 98.44%），表明附生细菌群落对培养基中 As(V) 的还原有重要贡献。当暴露于 As(V) 时，附生细菌群落的存在显著增加了植物对砷的积累（最高可达 2.06 倍）。结果还表明，附生细菌群落对 As(III) 外排的贡献很小。砷代谢基因的定量 PCR 显示，附生细菌群落中呼吸砷酸盐（As(V)) 还原酶基因 (arrA) 占主导地位，这可能在水生环境中砷酸盐（As(V)) 的还原中发挥重要作用。arrA 基因的系统发育分析揭示了砷酸盐（As(V)) 呼吸细菌的广泛分布和多样性。这些结果强调了与沉水水生植物相关的附生细菌群落对湿地和水环境中砷生物地球化学的重大影响。
