The Essential Role of OmpR in Adapting to the High Osmolarity and Its Regulation on the Tetrathionate-Metabolic Pathway.

spp. are prevalent in acid mine drainage, and they have been widely used in biomining for extracting nonferrous metals from ores. The osmotic stress generated by elevated concentrations of inorganic ions is a severe challenge for the growth of spp. in the bioleaching process; however, the adaptation mechanism of these bacteria to high osmotic pressure remains unclear. In this study, bioinformatics analysis indicated that the osmotic stress response two-component system EnvZ-OmpR is widely distributed in spp., while OmpRs from spp. exhibited a far more evolutionary relationship with the well-studied OmpRs in and . The growth measurement of an () -knockout strain demonstrated that OmpR is essential in the adaptation of this bacterium to high osmotic stress. The overall impact of OmpR on the various metabolic and regulatory systems of was revealed by transcriptome analysis. The OmpR binding sequences of differentially expressed genes (DEGs) were predicted, and the OmpR box motif in was analysed. The direct and negative regulation of EnvZ-OmpR on the tetrathionate-metabolic () cluster in was discovered for the first time, and a co-regulation mode mediated by EnvZ-OmpR and RsrS-RsrR for the tetrathionate intermediate thiosulfate-oxidizing (SI) pathway in this microorganism was proposed. This study reveals that EnvZ-OmpR is an indispensable regulatory system for the ability of to cope with high osmotic stress and the significance of EnvZ-OmpR on the regulation of sulfur metabolism in adapting to the high-salt environment.