Naz Naghma, Young Hilary K, Ahmed Nuzhat, Gadd Geoffrey M
Division of Environmental and Applied Biology, Biological Sciences Institute, School of Life Sciences, University of Dundee, Dundee DD1 4HN, Scotland, United Kingdom.
Appl Environ Microbiol. 2005 Aug;71(8):4610-8. doi: 10.1128/AEM.71.8.4610-4618.2005.
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.
研究了四种硫酸盐还原菌(SRB)的纯培养物和一种混合培养物对镉(0.1至1.0 mM)的抗性。在存在不同浓度氯化镉的情况下,针对碳源(乳酸)氧化和硫酸盐还原监测细菌的生长。两株脱硫脱硫弧菌DSM 1926和多噬脱硫球菌DSM 2059对镉(0.5 mM)表现出最高抗性。对这两株菌进行透射电子显微镜观察,发现镉在细胞内和周质中积累。使用针对smtAB、cadAC和cadD基因的探针进行斑点印迹DNA杂交,表明在所测试的SRB中存在类似的重金属抗性遗传决定因素。对扩增DNA进行测序,结果显示所有SRB菌株与编码集胞藻金属硫蛋白的已知smtAB基因具有很强的核苷酸同源性。在挪威脱硫微菌I1和脱硫脱硫弧菌DSM 1926的克隆扩增DNA中也检测到与已知重金属转运ATP酶的蛋白质同源性,表明这两株菌中存在多种金属抗性遗传机制。