Project description:Chemolithoautotrophic sulfur-oxidizing bacteria (SOB) are crucial key players in biotechnological processes to remove hydrogen sulfide from sour gas streams. Several different haloalkaliphilic SOB have been detected and isolated from lab- and full-scale facilities, which all performed differently considering end product yields (sulfur and sulfate) and conversion rates. Understanding and regulating bacterial community dynamics in biodesulfurization processes will enable optimization of the process operation. We developed quantitative PCR (qPCR) assays to quantify haloalkaliphilic sulfur-oxidizing gammaproteobacterial species Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus, and Thioalkalibacter halophilus that dominate bacterial communities of biodesulfurization lab- and full-scale installations at haloalkaline conditions. The specificity and PCR efficiency of novel primer sets were evaluated using pure cultures of these target species. We further validated the qPCR assays by quantification of target organisms in five globally distributed full-scale biodesulfurization installations. The qPCR assays perform a sensitive and accurate quantification of Alkalilimnicola ehrlichii, Thioalkalivibrio sulfidiphilus and Thioalkalibacter halophilus, thus providing rapid and valuable insights into process performance and SOB growth dynamics in gas biodesulfurization systems.
Project description:Cells respond to environmental stress by regulating gene expression at the level of both transcription and translation. The ~50 modified ribonucleotides of the human epitranscriptome contribute to the latter, with mounting evidence that dynamic regulation of tRNA wobble modifications leads to selective translation of stress response proteins from codon-biased genes. Here we show that the response of human HepG2 cells to arsenite exposure is regulated by the availability of queuine, a micronutrient and essential precursor to the wobble modification queuosine (Q) on tRNAs reading GUN codons. Among oxidizing and alkylating agents at equitoxic concentrations, arsenite exposure caused an oxidant-specific increase in Q that correlated with up-regulation of proteins from codon-biased genes involved in energy metabolism. Limiting queuine increased arsenite-induced cell death, altered translation, increased reactive oxygen species levels, and caused mitochondrial dysfunction. In addition to revealing a new epitranscriptomic facet of arsenite toxicity and response, our results highlight the mechanistic links between environmental exposures, stress tolerance, and micronutrients.
Project description:Cells respond to environmental stress by regulating gene expression at the level of both transcription and translation. The ~50 modified ribonucleotides of the human epitranscriptome contribute to the latter, with mounting evidence that dynamic regulation of tRNA wobble modifications leads to selective translation of stress response proteins from codon-biased genes. Here we show that the response of human HepG2 cells to arsenite exposure is regulated by the availability of queuine, a micronutrient and essential precursor to the wobble modification queuosine (Q) on tRNAs reading GUN codons. Among oxidizing and alkylating agents at equitoxic concentrations, arsenite exposure caused an oxidant-specific increase in Q that correlated with up-regulation of proteins from codon-biased genes involved in energy metabolism. Limiting queuine increased arsenite-induced cell death, altered translation, increased reactive oxygen species levels, and caused mitochondrial dysfunction. In addition to revealing a new epitranscriptomic facet of arsenite toxicity and response, our results highlight the mechanistic links between environmental exposures, stress tolerance, and micronutrients.
