Abstract
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.
Highlights
Arsenic (As) is considered as toxic metalloids that widely distributes on the earth’s surface
Heterotrophic cytoplasmic arsenatereducing bacteria can reduce arsenate to arsenite by using their cytoplasmic arsenate reductase and this activity is considered as a detoxification process [6]
The arsenite oxidation of heterotrophic arseniteoxidizing bacteria (HAOs) is considered as a detoxification process because these microbes unable to gain any energy from this activity to produce their cell materials [11]
Summary
Arsenic (As) is considered as toxic metalloids that widely distributes on the earth’s surface. Heterotrophic cytoplasmic arsenatereducing bacteria can reduce arsenate to arsenite by using their cytoplasmic arsenate reductase (arcC) and this activity is considered as a detoxification process [6]. Dissimilatory arsenate reducing bacteria is considered as an arsenate respirer These microbes enable to transform arsenate to arsenite by their respiration process and gain energy for growth [7]. The arsenite oxidation of heterotrophic arseniteoxidizing bacteria (HAOs) is considered as a detoxification process because these microbes unable to gain any energy from this activity to produce their cell materials [11]. While chemoautotrophic arsenite oxidizing bacteria (CAOs) are regarded as an arsenite eater They can conserve energy for growth through their oxidation process [12]. Since several arsenite oxidizing bacteria were found in various rich As concentration environments, the purpose of this study was to investigate the communities of arsenite-oxidizing bacteria in groundwater with low As concentration to better understand their inherent distributions in this natural environment
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