| Summary: | 碩士 === 臺灣大學 === 生物環境系統工程學研究所 === 98 === The contamination of arsenic in groundwater has caused a serious public health crisis. Over millions of people are exposing to arsenic by drinking arsenic contaminated well water, which occurred in the south-west part of Taiwan in 1960s, resulting in the Blackfoot disease and various cancers. Evidences have suggested that arsenic released from solid phase into aqueous phase is mediated by microbial interaction. However, the relationship of arsenic mobilization and microbial interaction in aquifer are poorly studied. Strain L2 is an arsenate-reducing bacterium isolated from arsenic contaminated groundwater. Analysis of 16S rDNA showed that it belongs to the genus of Citrobacter. In this study, the electron donor and acceptor tests, growth curve, and arsenate transformation of strain L2 was investigated. Strain L2 was able to reduce 200 μM (15 ppm) arsenate in less than 2 days. PCR amplification showed that strain L2 contained arsC gene, which encodes the cytoplasmic arsenate reductase. Moreover, transposon mutagenesis was performed to identify novel genes involved in arsenate reduction. Identification of arsenate reduction mutants showed that the disruption of mogA resulted in the decrease of arsenate reduction ability. MogA encodes the molybdopterin biosynthesis protein, which involves in the biosynthetic pathway of molybdenum cofactor formation. The physiological property and biochemical insights of mogA mutant with arsenate reduction were discussed.
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