Characterization of arsenite-oxidizing bacteria to decipher their role in arsenic bioremediation

Abstract

High arsenic groundwater contamination causes serious health risks in many developing countries, particularly in India and Bangladesh. The arsenic fluxes in aquifers are primarily controlled by bacterial populations through biogeochemical cycle. In this present study, two gram-positive rod-shaped bacteria were isolated from shallow aquifers of Bhojpur district in Bihar during the early winter season, able to withstand arsenite (As³⁺) concentration upto 70 mM and 1000 mM of arsenate (As⁵⁺) concentration. They showed high resistance to heavy metals up to 30 mM and utilized some complex sugars along with different carbon sources. Growth at wide range of temperature, pH and salinity were observed. Both these isolates showed high efficiency in converting As³⁺ into less toxic concentrations of As⁵⁺ respectively from arsenic enriched culture media. Along with superior arsenic transformation and arsenic resistance abilities, the isolates showed a wide variety of metabolic capacity in terms of utilizing a variety of carbon sources under aerobic conditions, respectively. This study reports the potential As³⁺-oxidizing bacteria that can play an important role in subsurface arsenic transformation that will aid in designing future bioremediation strategy for the arsenic affected areas.

Keywords:

• Arsenic
• bacteria
• bioremediation
• characterization
• groundwater
• resistance

Acknowledgments

The authors would like to acknowledge the Department of Science and Technology, Government of India, for providing financial assistance to proceed with the research work. We would also like to extend our gratitude to National Institute of Technology, Rourkela for providing suitable infrastructure facilities. Finally, we would like to thank Prof. Ashok Ghosh for his benevolent support during our sample collection from Bihar.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the (Sanction No. YSS/2015/001911), Department of Science and Technology, Ministry of Science and Technology, India.