Isolation of an arsenite-oxidizing bacterium in the arsenic contaminated shallow alluvial aquifer in the Blackfoot disease endemic area: Its potential for remediation of arsenic in groundwater

摘要

Arsenic poisoning affects millions of people worldwide. Although groundwater arsenic problems in Taiwan have been recognized since 1960s, few reports have been published about the relationship between microbes and arsenic release into groundwater. In this study, we isolated an indigenous arsenite-oxidizing bacterium As7325 from arsenic contaminated shallow alluvial aquifer in the Blackfoot Disease endemic area. The Basic Local Alignment Search Tool (BLAST) search of the 16S rRNA showed that strain As7325 belongs to the genus of Pseudomonas. The optimal temperature for growth is 30 °C. Bacterial strain As7325 is a facultative anaerobe which could grow in artificial groundwater amended with acetate, lactate, and succinate. In addition, the cytoplasmic arsenite oxidase aoxB was amplified by PCR, suggesting that strain As7325 contains arsenic oxidation/detoxification mechanisms. Furthermore, strain As7325 was able to oxidize 30 μM (-2200 μg/L) arsenite that was previously reported in the arsenic contaminated shallow alluvial aquifer in the blackfoot disease endemic area within 1 day using environmental groundwater under aerobic conditions. We also used As7325 as a biosorbent to remove arsenic in groundwater. The results showed that 5 g/L biomass of the bacteria can adsorb 500 and 1000 ppb arsenate with 37% and 60%, respectively within 2 days. The adsorption efficiency for 500 and 1000 ppb arsenate reached 87% and 100%, respectively at 6-day. Therefore, strain As7325 shows its great potential for bioremediation of groundwater arsenic in situ.