As contamination in groundwater has become one of the global problems. It has been reported that million people around the world get adverse effects on their health by direct and indirect As-contaminated groundwater consumption. In groundwater, the most abundant As species are arsenite (As3+) and arsenate (As5+). Arsenite is more toxic and mobile than arsenate. Consequently, arsenite oxidation is considered as an important process in groundwater As bioremediation. It has been reported that arsenite-oxidizing bacteria play an important role in reducing As toxicity in contaminated groundwater environment. A functional gene involved in arsenite oxidation is aioA gene. The key objective of this study was to investigate the arsenite-oxidizing bacteria in groundwater with low arsenic concentration in Rayong province, Thailand. The results showed that the arsenite-oxidizing bacteria were detected in groundwater with low arsenic concentration. Phylogenetic analysis revealed that they were closely related to Rhizobium sp., Bradyrhizobiaceae sp., Hydrogenophaga sp., and Stenotrophomonas sp. The knowledge gained from this study will help better understand the distribution of arsenite-oxidizing bacteria in groundwater with low As concentration.
Millions of people around the world potentially expose to arsenic (As) contaminated groundwater. Besides, the dominant form of As in groundwater is arsenite (As+3) and is more toxic than arsenate (As+5). This study integrated the microbial investigation, geochemical modeling, and multivariate statistical analysis to investigate the arsenite-oxidizing bacteria community from As-contaminated groundwater and its environmental influencing factors in order to understand and further develop the in-situ arsenic bioremediation technology. Microbial investigation was focusing on the detection and identification of native arsenite-oxidizing bacterial community using PCR-DGGE, cloning and sequencing of arsenite oxidase (aoxB) gene amplicons. Nine groundwater samples were collected from the gold mine and residential areas. Surface water and soil samples were also collected from upstream, within, and downstream of the gold mining area and then were compared each other. The results showed that the majority of arsenite-oxidizing bacteria was related to α-, β-proteobacteria-like clusters in which the environmental media divided them into separated clusters. Many of groundwater clones revealed affiliated to the member of β-proteobacteria class where it was contributed by Hydrogenophaga, Burkholderia, Alcaligenes, Variovorax, Thiomonas, and Cupriavidus genera. This finding implied that these native arsenite-oxidizing bacteria might play a key role in controlling an As geochemistry in As-contaminated groundwater. Moreover, PHREEQC geochemical modeling of As and multivariate statistical analysis revealed that As presented as As5+ in most groundwater samples. However, the speciations seemed to be not driven by the arsenite-oxidizing bacterial community, but geochemical charateristics of groundwater, which were pH, ORP, and DO, influence on the shape their communities significantly, while As, and Fe concentrations play a minor role.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.