Characterization of Dietzia natronolimnaea ASO3 Isolated from Arsenic Anriched Water Sources for its Potential to Arsenic Resistance and Removal

Abstract

Introduction: Arsenic is a known toxic metalloid ubiquitous in nature and exposure can occur from natural and anthropogenic sources. In organic arsenic both arsenite and arsenate constitute the highest toxicological risk associated with arsenic in drinking water. This study presents the arsenic resistance and removal capacity of a bacterial strain indigenous to arsenic enriched water of Rautahat district, Nepal.

Methods: Identification was carried out by phenotypic and 16S rDNA sequence analysis. The optimal growth conditions regarding temperature, hydrogen ion concentration and salinity; growth kinetics in presence and absence of arsenic, determination of maximum arsenic tolerance concentration, sensitivity to antibiotics, plasmid mediated resistance as well as arsenate reduction and arsenite oxidation and finally arsenic removal potential was determined.

Results: The bacterium, Dietzia natronolimnaea ASO3 showed relatively high resistance to arsenate upto 37,460 mg/l and arsenite up to 374.6 mg/l. It showed optimal growth at 30°C in pH 8. The bacterium conferred resistance to penicillin and removed 47% of arsenite and 51% of arsenate from the medium amended with 200 mg/l arsenate and 74.92mg/l arsenite respectively.

Conclusion: The higher arsenic tolerance to both arsenate and arsenite species with potential for their removal can be explored further for arsenic mitigation and mobilization study.