人体肠道微生物对土壤砷的形态转化机制及其影响因素研究

砷对人体的健康风险是土壤砷污染研究的重要内容之一，明确人体肠道微生物对土壤砷的形态转化机理及影响因素，是这一领域未解决的关键科学问题之一。本项目拟通过体外培养和收集健康人的新鲜粪便等途径获取人体肠道微生物。在此基础上，明确人体肠道微生物对土壤中不同形态砷（矿物、有机质的吸附砷，含砷化合物等）、不同来源土壤砷的转化能力、速率和固液分配等，阐明砷转化及还原机制；明确人体肠道微生物对土壤砷形态转化的影响因素；对比体外消化/Caco-2细胞模型和小鼠实验评估土壤砷的人体生物有效性差异及影响因素，阐明人体肠道微生物转化后的不同形态砷的人体生物有效性，从不同个体、饮食习惯和土壤性质等方面，提出降低土壤砷的人体生物有效性的途径及策略。本项目的研究必将对土壤砷在人体胃肠道中的转化及赋存状态和人体吸收土壤中不同形态及价态的砷的准确判定提供依据，也将为土壤砷的人体的健康风险研究理论与方法起到很好的推动作用。

The human health risk of arsenic is one of the most concerned issues in soil arsenic contamination. The effect of human gut microbiota on soil arsenic speciation transformation mechanism and its influencing factors is still unknown. In this project, two kinds of methods, in vitro culture and collection of fresh feces from healthy people, will be used for collecting the human gut microbiota. The rate of arsenic speciation transformation by gut microbiota and distribution of arsenic in solid/liquid phases for the different forms of arsenic in the soil (such as mineral and organic matter adsorbed arsenic, compounds of arsenic, etc.) and different sources of arsenic in soil will be studied. In this process, the mechanism of arsenic transformation and reduction, the influence factors will also be studied. Comparison of in vitro digestion /Caco-2 cell model with mice experiment will be studied, and the two models will be use to assess the human bioavailability of soil arsenic. Factors affecting the effectiveness of assessing the human bioavailability will also be studied. Different individuals, eating habits and soil properties will be the important factors in assessing the human bioavailability of soil arsenic. The strategies to reduce human bioavailability of soil arsenic will be suggested. This research will not only provide some scientific understanding in the influence of human gut microbiota on soil arsenic speciation transformation mechanism and its health risk assessment but also play a significant role in promoting the theories and methods of human health risk of soil arsenic.