针对地下水/水田砷污染危害大、缺乏高效生物治理方法等问题，以相较其它水生生物具有更强砷耐受能力的水环境微生物——原生动物四膜虫为研究对象，考察15种四膜虫的砷半效应浓度，筛选到具有超强砷耐受能力的四膜虫种类；利用基因组数据鉴定15种四膜虫的砷甲基化酶基因，并考察不同浓度砷暴露下基因表达量和砷甲基化的能力；综合分析基因序列、表达量和砷甲基化能力间关系，鉴定出砷甲基化酶基因与酶活相关的关键位点，进而改造得到具有超高砷甲基化转化能力的砷甲基化酶基因；再利用四膜虫过表达技术在具有超强砷耐受能力的四膜虫中表达具有超高酶活的砷甲基化酶基因，实现对水体砷污染的超高效砷甲基化、减毒的生物治理。项目完成将是原生动物基因表达调控、砷甲基化酶基因分子进化和功能演化等方面的重要进展；构建的“超级四膜虫”，具有超强的砷耐受性和超高的砷甲基化能力，可通过高效转化无机砷来治理地下水/水田的砷污染危害，具有巨大应用潜力。

Focusing on the problems of arsenic pollutants in groundwater and paddy field, and lack of efficient bioremediation technology, we study the aquatic microorganism, protozoan Tetrahyema with more tolerance: detect and compare the half effect concentration (EC50) of As among 15 Tetrahymena species, and select the Tetrahymena species with the hightest EC50 (“super-species”); identify the arsenic methyltransferase (ArsM) genes of 15 Tetrahymena species, and detect their expression by RNA-seq and arsenic species by ICP-MS under arsenic treatment; identify the key sites of the enzyme activity according to the analysis of the relationship among the gene sequences, expression level and ability of methylation, and construct artificially the arsenic methyltransferase gene with the highest enzyme activity (“super-ArsM”); use the “super-species” to express the “super-ArsM” as the “super” Tetrahymena with efficient arsenic methylation and detoxification. The completion of project will be the progress of the gene regulation in protozoan and molecular evolution of ArsM genes, and Tetrahymena strains for methylating arsenic will be more efficient. All of them will be applicable to environmental samples and have great potential.