Copper resistance in Desulfovibrio strain R2.
ABSTRACT A sulfate-reducing bacterium, designated as strain R2, was isolated from wastewater of a ball-bearing manufacturing facility in Tomsk, Western Siberia. This isolate was resistant up to 800 mg Cu/l in the growth medium. By comparison, Cu-resistance of reference cultures of sulfate-reducing bacteria ranged from 50 to 75 mg Cu/l. Growth experiments with strain R2 showed that Cu was an essential trace element and, on one hand, enhanced growth at concentrations up to 10 mg/l but, on the other hand, the growth rate decreased and lag-period extended at copper concentrations of >50 mg/l. Phenotypic characteristics and a 1078 bp nucleotide sequence of the 16S rDNA placed strain R2 within the genus Desulfovibrio. Desulfovibrio R2 carried at least one plasmid of approximately of 23.1 kbp. A 636 bp fragment of the pcoR gene of the pco operon that encodes Cu resistance was amplified by PCR from plasmid DNA of strain R2. The pco genes are involved in Cu-resistance in some enteric and aerobic soil bacteria. Desulfovibrio R2 is a prospective strain for bioremediation purposes and for developing a homologous system for transformation of Cu-resistance in sulfate-reducing bacteria.
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ABSTRACT: A sulfate-reducing bacterial culture was successfully enriched from the seed sludge of anaerobic sludge digester. Sulfate-reducing bacteria (SRB) in the enriched culture (around 42%) were characterized by fluorescence in situ hybridization (FISH) with group and genus specific 16S rRNA-targeted oligonucleotide probes. Desulfosarcina, Desulfococcus, Desulfofaba, and Desulfofrigus spp. were identified as the dominant species of the enriched SRB. Subsequently, batch experiments were conducted at initial copper and sulfate concentrations of 10 and 300mg/L, respectively, to quantify the ability of the enriched SRB in simultaneous sulfate reduction and copper removal. Sulfate reduction efficiencies of the culture in the absence (biotic system without copper, BS-1) and the presence (biotic system with copper, BS-2) of copper were 96.8 and 98.8%, respectively, after 6 days. In BS-2, 99.2% copper removal was observed after 1 day. However, 67% of copper was removed by chemical precipitation and bioaccumulation. No significant inhibition of bacterial growth was observed at the copper concentration studied, that is, 10mg/L. Chemical precipitation as hydroxide/carbonate caused a copper removal of 44% in AS-1 (abiotic system without lactate) and 36% in AS-2 (abiotic system with lactate), after 6 days. However, the majority of copper was removed as copper sulfide well before the occurrence of copper hydroxide precipitation. Energy dispersive X-ray spectroscopy (EDS) analysis of the precipitates obtained from biotic and abiotic systems confirmed the origin of copper sulfide as the result of SRB. As a whole, the results of this study could be useful to understand the mechanisms of copper removal, i.e. chemical precipitation, bioprecipitation and biosorption/bioaccumulation during sulfate reduction by SRB.Environmental Engineering Science 06/2009; 26(6):1087-1096. DOI:10.1089/ees.2008.0270 · 0.93 Impact Factor
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ABSTRACT: The purpose of this work was to isolate Cu-tolerant sulfate-reducers that could be used to produce copper sulfides under pure culture conditions. Three sulfate-reducing bacteria were isolated from wastewater effluents of a zinc-smelter in the Urals and their tolerance to copper varied between 325 and 2600 mg Cu l. Analysis of 16S rRNA gene sequences placed the isolates in the genus Desulfovibrio. The isolates showed pronounced saccharolytic growth. Growing cultures precipitated Cu as covellite (CuS) within less than a week. Extended incubation for 1 month lead to the formation of chalcocite (Cu2S) and chalcopyrite (CuFeS2).Geomicrobiology 06/2008; 25(5):219-227. DOI:10.1080/01490450802153124 · 1.80 Impact Factor
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ABSTRACT: The bacterial community structure in epilithic biofilms within 18 different streams was characterised using a community DNA fingerprinting technique (automated ribosomal intergenic spacer analysis—ARISA). Each stream has previously been described in terms of the dominant catchment land use, relative level of human disturbance and using a broad suite of water quality variables. Combination of ARISA with multivariate statistical analysis and ordination revealed that bacterial communities in streams located within rural catchments were significantly different to those within urban catchments. Broad-scale catchment land use described the largest component of the observed variation with no single water quality variable found to be a dominant determinant of the observed bacterial community variability, assessed using distance based redundancy analysis (dbRDA) of the ARISA data. This study highlights the potential of bacterial ARISA to provide a rapid and cost-effective approach to monitor the impact of catchment land use on aquatic ecosystems, such as the influence of encroaching urban development on the ecological health of rural streams.Ecological Indicators 09/2009; 9(5-9):848-855. DOI:10.1016/j.ecolind.2008.10.001 · 3.23 Impact Factor