Identification of genes conferring arsenic resistance to Escherichia coli from an effluent treatment plant sludge metagenomic library

• Published in: FEMS microbiology ecology 2009-01, Vol.67 (1), p.130-139
• Main Authors: Chauhan, Nar Singh, Ranjan, Ravi, Purohit, Hemant J., Kalia, Vipin C., Sharma, Rakesh
• Format: Article
• Language: English
• Subjects: acetyltransferase; Acetyltransferases - chemistry; Acetyltransferases - genetics; Amino Acid Sequence; Anaeromyxobacter dehalogenans; Animal, plant and microbial ecology; Antimony; Arsenates; Arsenates - pharmacology; Arsenic; Arsenic - pharmacology; arsenic resistance; Arsenite; Bacteria; Bacteriology; Biological and medical sciences; Burkholderia; Burkholderia vietnamiensis; Cloning; Communities; Culture; Deoxyribonucleic acid; DNA; Drug Resistance, Bacterial - genetics; E coli; Ecology; Effluent treatment; Efflux; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - genetics; Escherichia coli - isolation & purification; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - genetics; Fundamental and applied biological sciences. Psychology; Gene pool; Genes; Genomes; Genomic Library; Homology; Industrial effluents; Industrial Waste; Industrial wastewater; Libraries; metagenomic; Microbial ecology; Microbial Sensitivity Tests; Microbiology; Microorganisms; Miscellaneous; Molecular Sequence Data; Reductases; Sequence Analysis, DNA; Sewage - microbiology; Sludge; Sodium; Sodium arsenate; Waste Disposal, Fluid - methods; Wastewater treatment; Water treatment
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/j.1574-6941.2008.00613.x

Abstract The majority of bacteria elude culture in the laboratory. A metagenomic approach provides culture-independent access to the gene pool of the whole bacterial community. A metagenomic library was constructed from an industrial effluent treatment plant sludge containing about 1.25 Gb of microbial community DNA. Two arsenic-resistant clones were selected from the metagenomic library. Clones MT3 and MT6 had eight- and 18-fold higher resistance to sodium arsenate in comparison with the parent strain, respectively. The clones also showed increased resistance to arsenite but not to antimony. Sequence analysis of the clones revealed genes encoding for putative arsenate reductases and arsenite efflux pumps. A novel arsenate resistance gene (arsN) encoding a protein with similarity to acetyltransferases was identified from clone MT6. ArsN homologues were found to be closely associated with arsenic resistance genes in many bacterial genomes. ArsN homologues were found fused to putative arsenate reductases in Methylibium petroleiphilum PM1 and Anaeromyxobacter dehalogenans 2CP-C and with a putative arsenite chaperone in Burkholderia vietnamiensis G4. ArsN alone resulted in an approximately sixfold higher resistance to sodium arsenate in wild-type Escherichia coli W3110.