College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, People's Republic of China.
Research Center for Eco-Environment Sciences, Chinese Academy of Sciences, Beijing 100085, People's Republic of China.
Environ Sci Technol. 2020 Apr 7;54(7):4432-4442. doi: 10.1021/acs.est.9b07235. Epub 2020 Mar 20.
The importance of arsenic metabolism by gut microbiota has been evidenced in risk characterization from As exposures. In this study, we evaluated the metabolic potency of human gut microbiota toward As(V)-sorbed goethite and jarosite, presenting different behaviors of As release, and the solid-liquid transformation and partitioning. The release of As occurred mainly in the small intestinal phase for jarosite and in the colon phase for goethite, respectively. We found higher degree of As(V) and Fe(III) reduction by human gut microbiota in the colon digests of goethite than jarosite. Speciation analysis using high-performance liquid chromatography coupled with inductively coupled plasma mass spectrometry and X-ray absorption near-edge spectroscopy, revealed that 43.2% and 8.5% of total As was present as As(III) in the liquid and solid phase, respectively, after goethite incubation, whereas almost all generated As(III) was in the colon digests of jarosite. Therefore, As bioaccessibility in human gastrointestinal tract was predominantly contributed to Fe(III) dissolution in jarosite, and to microbial reduction of Fe(III) and As(V) in goethite. It expanded our knowledge on the role of Fe minerals in human health risk assessment associated with soil As exposures.
肠道微生物对砷代谢的重要性已在砷暴露风险特征中得到证实。在本研究中，我们评估了人类肠道微生物对砷吸附的针铁矿和黄钾铁矾的代谢能力，这两种矿物表现出不同的砷释放行为、固-液转化和分配行为。砷的释放主要发生在黄钾铁矾的小肠阶段和针铁矿的结肠阶段。我们发现，在针铁矿结肠消化物中，人类肠道微生物对砷(V)和三价铁的还原程度高于黄钾铁矾。使用高效液相色谱-电感耦合等离子体质谱和 X 射线吸收近边光谱的形态分析表明，针铁矿孵育后，液体和固体相中分别有 43.2%和 8.5%的总砷以三价砷的形式存在，而黄钾铁矾的结肠消化物中几乎全部生成了三价砷。因此，在人类胃肠道中，砷的生物可利用性主要归因于黄钾铁矾中三价铁的溶解，以及针铁矿中三价铁和砷(V)的微生物还原。这扩展了我们对与土壤砷暴露相关的人类健康风险评估中铁矿物作用的认识。
