Project description:Cupriavidus metallidurans CH34 is a metal resistant beta-proteobacterium. The genome of this bacterium contain many genes involved in heavy metal resistance. Gene expression of C. metallidurans was studied after the addition of of Zn(II), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II) or Co(II). Keywords: Heavy metal stress response
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance
Project description:Background: The high number of heavy metal resistance genes in the soil bacterium Cupriavidus metallidurans CH34 makes it an interesting model organism to study microbial responses to heavy metals. Results: In this study the transcriptional response of this bacterium was measured after challenging it to a wide range of sub-lethal concentrations of various essential or toxic metals. Considering the global transcriptional responses for each challenge as well as by identifying the overlap in upregulated genes between different metal responses, the sixteen metals could be clustered in three different groups. Additionally, next to the assessment of the transcriptional response of already known metal resistance genes, new metal response gene clusters were identified. The majority of the metal response loci showed similar expression profiles when cells were exposed to different metals, suggesting complex cross-talk at transcriptional level between the different metal responses. The highly redundant nature of these metal resistant regions – illustrated by the large number of paralogous genes – combined with the phylogenetic distribution of these metal response regions within evolutionary related and other metal resistant bacteria, provides important insights on the recent evolution of this naturally soil dwelling bacterium towards a highly metal-resistant strain found in harsh and anthropogenic environments. Conclusions: The metal-resistant soil bacterium Cupriavidus metallidurans CH34 displays myriads of gene expression patterns when exposed to a wide range of heavy metals at non-lethal concentrations. The interplay between the different gene expression clusters points towards a complex cross-regulated regulatory network governing heavy metal resistance in C. metallidurans CH34. Keywords: Cupriavidus metallidurans CH34, transcriptional regulation, heavy metal resistance Two-condition experiments. Comparing samples after induction with heavy metals versus non-induced samples. Biological duplicate or triplicate. Each array contains 3 or 4 technical replicates.
Project description:The weathering of volcanic minerals makes a significant contribution to the global silicate weathering budget, influencing carbon dioxide drawdown and climate control. Basalt rocks may account for over 30% of the global carbon dioxide drawdown in silicate weathering. Yet the genetics of biological rock weathering are unknown. For the first time, we apply a DNA microarray to investigate the genes involved in weathering by the heavy metal resistant organism, Cupriavidus metallidurans CH34; in particular we investigate the sequestering of iron. The results show that the bacterium sequesters iron in the ferrous state (FeII); therefore, not requiring siderophores. Instead an energy efficient process involving upregulation of large porins is employed concomitantly with genes associated with biofilm formation. We hypothesise that rock weathering is induced by changes in chemical equilibrium at the microbe-mineral interface, reducing the saturation state of iron. We also demonstrate that low concentrations of metals in the basalt induce heavy metal resistant genes. Volcanic environments are analogous to some of the earliest environments on Earth. These results not only elucidate the mechanisms by which microorganisms might have sequestered nutrients on the early Earth but they also provide an explanation for the evolution of multiple heavy metal resistance genes long before the creation of contaminated industrial biotopes by human activity.
Project description:Cupriavidus metallidurans CH34 is a metal resistant beta-proteobacterium. The genome of this bacterium contain many genes involved in heavy metal resistance. Gene expression of C. metallidurans was studied after the addition of of Zn(II), Cd(II), Cu(II), Ni(II), Pb(II), Hg(II) or Co(II). Keywords: Heavy metal stress response Cultures of C. metallidurans CH34 were grown at 30°C until OD reached 0.6 (mid- exponential phase cultures). Heavy metals (0.8 mM of Zn(II), 0.5 mM of Cd(II), 0.1 mM of Cu(II), 0.6 mM of Ni(II), 0.4 mM of Pb(II), 5 uM of Hg(II) and 0.5 mM of Co(II)) were added to the culture for 30 minutes induction time. Total RNA was extracted, reverse-transcribed and labeled with Cy3-dCTP for the control (without metal) and with Cy5-dCTP for each conditions (challenged with one metal). Labeled cDNA were (control and one condition) added to a spotted slide for overnight hybridization at 42°C. Slides were scanned with a laser at 532 and 635 nm.
Project description:The weathering of volcanic minerals makes a significant contribution to the global silicate weathering budget, influencing carbon dioxide drawdown and climate control. Basalt rocks may account for over 30% of the global carbon dioxide drawdown in silicate weathering. Yet the genetics of biological rock weathering are unknown. For the first time, we apply a DNA microarray to investigate the genes involved in weathering by the heavy metal resistant organism, Cupriavidus metallidurans CH34; in particular we investigate the sequestering of iron. The results show that the bacterium sequesters iron in the ferrous state (FeII); therefore, not requiring siderophores. Instead an energy efficient process involving upregulation of large porins is employed concomitantly with genes associated with biofilm formation. We hypothesise that rock weathering is induced by changes in chemical equilibrium at the microbe-mineral interface, reducing the saturation state of iron. We also demonstrate that low concentrations of metals in the basalt induce heavy metal resistant genes. Volcanic environments are analogous to some of the earliest environments on Earth. These results not only elucidate the mechanisms by which microorganisms might have sequestered nutrients on the early Earth but they also provide an explanation for the evolution of multiple heavy metal resistance genes long before the creation of contaminated industrial biotopes by human activity. Cultures of Cupriavidus metallidurans CH34 were grown in Tris buffered medium MM284 media (with iron), MM284 without iron and MM284 without iron with sterilized basalt at 25 rpm, 30°C until mid-log phase. RNA was extracted from the cells. Three biological replicates of both samples were differentially labeled (resp. Cy3 and Cy5) and hybridized to three CH34 60-mer oligonucleotide glass-spotted microarray carrying three technical repeats.