title: Cadmium accumulation and DNA homology with metal resistance genes in sulfate-reducing bacteria.
abstract: Cadmium resistance (0.1 to 1.0 mM) was studied in four pure and one mixed culture of sulfate-reducing bacteria (SRB). The growth of the bacteria was monitored with respect to carbon source (lactate) oxidation and sulfate reduction in the presence of various concentrations of cadmium chloride. Two strains Desulfovibrio desulfuricans DSM 1926 and Desulfococcus multivorans DSM 2059 showed the highest resistance to cadmium (0.5 mM). Transmission electron microscopy of the two strains showed intracellular and periplasmic accumulation of cadmium. Dot blot DNA hybridization using the probes for the smtAB, cadAC, and cadD genes indicated the presence of similar genetic determinants of heavy metal resistance in the SRB tested. DNA sequencing of the amplified DNA showed strong nucleotide homology in all the SRB strains with the known smtAB genes encoding synechococcal metallothioneins. Protein homology with the known heavy metal-translocating ATPases was also detected in the cloned amplified DNA of Desulfomicrobium norvegicum I1 and Desulfovibrio desulfuricans DSM 1926, suggesting the presence of multiple genetic mechanisms of metal resistance in the two strains.
authors.affiliation: Division of Environmental and Applied Biology, Biological Sciences Institute, School of Life Sciences, University of Dundee, Dundee DD1 4HN, Scotland, United Kingdom. naghmanaz@yahoo.com
authors.forename: Naghma
authors.initials: N
authors.lastname: Naz
authors.forename: Hilary K
authors.initials: HK
authors.lastname: Young
authors.forename: Nuzhat
authors.initials: N
authors.lastname: Ahmed
authors.forename: Geoffrey M
authors.initials: GM
authors.lastname: Gadd
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002104:Cadmium / Q000378:metabolism* / Q000494:pharmacology*; D004268:DNA-Binding Proteins / Q000235:genetics; D020564:Deltaproteobacteria / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D003901:Desulfovibrio / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D008668:Metallothionein / Q000235:genetics; D019216:Metals, Heavy / Q000378:metabolism / Q000494:pharmacology; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D012097:Repressor Proteins / Q000235:genetics; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D016999:Sulfur-Reducing Bacteria / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D019216:Metals, Heavy; D012097:Repressor Proteins; C080048:smtA protein, Synechococcus; D002104:Cadmium; D008668:Metallothionein