title: Characterization of arsenite-oxidizing bacteria isolated from arsenic-contaminated groundwater of West Bengal.
abstract: Nine arsenic (As)-resistant bacterial strains isolated from As-rich groundwater samples of West Bengal were characterized to elucidate their potential in geomicrobial transformation and bioremediation aspects. The 16S rRNA gene-based phylogenetic analysis revealed that the strains were affiliated with genera Actinobacteria, Microbacterium, Pseudomonas and Rhizobium. The strains exhibited high resistance to As [Minimum inhibitory concentration (MIC) ≥ 10 mM As(3+) and MIC ≥ 450 mM As(5+)] and other heavy metals, e.g., Cu(2+), Cr(2+), Ni(2+), etc. (MIC ≥ 2 mM) as well as As transformation (As(3+) oxidation and As(5+) reduction) capabilities. Their ability to utilize diverse carbon source(s) including hydrocarbons and different alternative electron acceptor(s) (As(5+), SO4(2-), S2O3(2-), etc.) during anaerobic growth was noted. Growth at wide range of pH, temperature and salinity, production of siderophore and biofilm were observed. Together with these, growth pattern and transformation kinetics indicated a high As(3+) oxidation activity of the isolates Rhizobium sp. CAS934i, Microbacterium sp. CAS905i and Pseudomonas sp. CAS912i. A positive relation between high As(3+) resistance and As(3+) oxidation and the supportive role of As(3+) in bacterial growth was noted. The results highlighted As(3+) oxidation process and metabolic repertory of strains indigenous to contaminated groundwater and indicates their potential in As(3+) detoxification. Thus, such metabolically well equipped bacterial strains with highest As(3+) oxidation activities may be used for bioremediation of As contaminated water and effluents in the near future.
authors.affiliation: a Department of Biotechnology , Indian Institute of Technology , Kharagpur , India.
authors.forename: Dhiraj
authors.initials: D
authors.lastname: Paul
authors.forename: Soumya
authors.initials: S
authors.lastname: Poddar
authors.forename: Pinaki
authors.initials: P
authors.lastname: Sar
mesh_terms: D001151:Arsenic / Q000378:metabolism / Q000633:toxicity; D018053:Arsenites / Q000378:metabolism*; D001419:Bacteria / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D020459:Genes, rRNA; D060587:Groundwater / Q000382:microbiology*; D007194:India; D019216:Metals, Heavy / Q000633:toxicity; D008826:Microbial Sensitivity Tests; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity
chemical_list: D018053:Arsenites; D019216:Metals, Heavy; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical; C015001:arsenite; D001151:Arsenic
keywords: Arsenic; arsenate reduction; arsenite oxidation; groundwater; indigenous bacteria