Key Laboratory of Urban Environment and Health , Institute of Urban Environment, Chinese Academy of Sciences , 1799 Jimei Road , Xiamen 361021 , China.
University of Chinese Academy of Sciences , 19A Yuquan Road , Beijing 100049 , China.
Environ Sci Technol. 2019 Apr 2;53(7):3841-3849. doi: 10.1021/acs.est.8b06695. Epub 2019 Mar 21.
Arsenic biotransformation mediated by gut microbiota can affect arsenic bioavailability and microbial community. Arsenic species, arsenic biotransformation genes (ABGs), and the composition of gut microbial community were characterized after the earthworm Metaphire sieboldi was cultured in soils spiked with different arsenic concentrations. Arsenite (As(III)) was the major component in the earthworm gut, whereas arsenate (As(V)) was predominant in the soil. A total of 16 ABGs were quantified by high-throughput quantitative polymerase chain reaction (HT-qPCR). Genes involved in arsenic redox and efflux were predominant in all samples, and the abundance of ABGs involved in arsenic methylation and demethylation in the gut was very low. These results reveal that the earthworm gut can be a reservoir of microbes with the capability of reducing As(V) and extruding As(III) but with little methylation of arsenic. Moreover, gut microbial communities were dominated by Actinobacteria, Firmicutes, and Proteobacteria at the phylum level and were considerably different from those in the surrounding soil. Our work demonstrates that exposure to As(V) disturbs the gut microbiota of earthworms and provides some insights into arsenic biotransformation in the earthworm gut.
肠道微生物介导的砷生物转化可以影响砷的生物利用度和微生物群落。在用不同浓度砷污染的土壤中培养赤子爱胜蚓后，对其肠道中的砷形态、砷生物转化基因（ABGs）和肠道微生物群落的组成进行了分析。结果表明，在蚯蚓肠道中，亚砷酸盐（As(III)）是主要成分，而在土壤中，砷酸盐（As(V)）则占优势。通过高通量定量聚合酶链反应（HT-qPCR）共定量了 16 个 ABGs。所有样品中均以涉及砷氧化还原和外排的基因为主，而肠道中参与砷甲基化和脱甲基化的 ABGs 丰度非常低。这些结果表明，蚯蚓肠道可能是具有还原 As(V)和排出 As(III)能力但砷甲基化能力较弱的微生物的储库。此外，肠道微生物群落以放线菌门、厚壁菌门和变形菌门为主，与周围土壤中的群落有很大的不同。本研究表明，砷暴露会扰乱蚯蚓的肠道微生物群，并为蚯蚓肠道中的砷生物转化提供了一些见解。
