Project description:The physiological and transcriptomic response of the metal resistant bacterium Cupriavidus metallidurans strain CH34 in response to stable (non-radioactive) strontium ions (Sr) was investigated. C. metallidurans CH34 could survive and proliferate in the presence of relatively high concentrations of SrCl2 (D10 is 70mM, MIC is 120 mM). Precipitation of Sr as strontium carbonate was observed in the culture during aerobic growth of CH34 in the presence of 60 mM SrCl2. To identify the cellular mechanisms involved in the bioprecipitation process, gene expression in the cells was analyzed after short-time (30 min) exposure to low (5 mM) and high (60 mM) concentrations of SrCl2. The transcription of the gene clusters annotated as hmyFCBA and czcCBADRS, coding for ion efflux pumps, was significantly induced following exposure to Sr, and not with Ca. There were also significant changes is the transcription of the genes encoding TctCBA proteins involved in citrate uptake and two hypothetical porin coding genes following exposure Sr and Ca. These results highlight a specific molecular response of bacterium Cupriavidus metallidurans CH34 to Sr, including the identification of putative Sr specific efflux pumps, and thus the potential of this bacterium to distinguish Sr from Ca. These findings will help to better understand natural Sr (and Ca) microbial weathering or mineralization processes in the environment, and could be of interest for bioremediation or bioprocessing of (radioactive) Sr-containing water, soil or waste.
Project description:The physiological and transcriptomic response of the metal resistant bacterium Cupriavidus metallidurans strain CH34 in response to stable (non-radioactive) strontium ions (Sr) was investigated. C. metallidurans CH34 could survive and proliferate in the presence of relatively high concentrations of SrCl2 (D10 is 70mM, MIC is 120 mM). Precipitation of Sr as strontium carbonate was observed in the culture during aerobic growth of CH34 in the presence of 60 mM SrCl2. To identify the cellular mechanisms involved in the bioprecipitation process, gene expression in the cells was analyzed after short-time (30 min) exposure to low (5 mM) and high (60 mM) concentrations of SrCl2. The transcription of the gene clusters annotated as hmyFCBA and czcCBADRS, coding for ion efflux pumps, was significantly induced following exposure to Sr, and not with Ca. There were also significant changes is the transcription of the genes encoding TctCBA proteins involved in citrate uptake and two hypothetical porin coding genes following exposure Sr and Ca. These results highlight a specific molecular response of bacterium Cupriavidus metallidurans CH34 to Sr, including the identification of putative Sr specific efflux pumps, and thus the potential of this bacterium to distinguish Sr from Ca. These findings will help to better understand natural Sr (and Ca) microbial weathering or mineralization processes in the environment, and could be of interest for bioremediation or bioprocessing of (radioactive) Sr-containing water, soil or waste. Two-condition experiments. Comparing samples after induction with metals (Sr, Ca) versus non-induced samples. Biological triplicate. Each array contains 3 technical replicates.