title: Identification of Differentially Expressed Genes duringBacillus subtilisSpore Outgrowth in High-Salinity Environments Using RNA Sequencing.
abstract: In its natural habitat, the soil bacteriumBacillus subtilisoften has to cope with fluctuating osmolality and nutrient availability. Upon nutrient depletion it can form dormant spores, which can revive to form vegetative cells when nutrients become available again. While the effects of salt stress on spore germination have been analyzed previously, detailed knowledge on the salt stress response during the subsequent outgrowth phase is lacking. In this study, we investigated the changes in gene expression duringB. subtilisoutgrowth in the presence of 1.2 M NaCl using RNA sequencing. In total, 402 different genes were upregulated and 632 genes were downregulated during 90 min of outgrowth in the presence of salt. The salt stress response of outgrowing spores largely resembled the osmospecific response of vegetative cells exposed to sustained high salinity and included strong upregulation of genes involved in osmoprotectant uptake and compatible solute synthesis. The σB-dependent general stress response typically triggered by salt shocks was not induced, whereas the σWregulon appears to play an important role for osmoadaptation of outgrowing spores. Furthermore, high salinity induced many changes in the membrane protein and transporter transcriptome. Overall, salt stress seemed to slow down the complex molecular reorganization processes ("ripening") of outgrowing spores by exerting detrimental effects on vegetative functions such as amino acid metabolism.
authors.affiliation: Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center Cologne, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Nagler
authors.affiliation: Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands.
authors.forename: Antonina O
authors.initials: AO
authors.lastname: Krawczyk
authors.affiliation: Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands.
authors.forename: Anne
authors.initials: A
authors.lastname: De Jong
authors.affiliation: Advanced Light and Electron Microscopy, Center for Biological Threats and Special Pathogens, Robert Koch Institute Berlin, Germany.
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Madela
authors.affiliation: Laboratory of Microbiology, Department of Biology, Philipps-University Marburg Marburg, Germany.
authors.forename: Tamara
authors.initials: T
authors.lastname: Hoffmann
authors.affiliation: Advanced Light and Electron Microscopy, Center for Biological Threats and Special Pathogens, Robert Koch Institute Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Laue
authors.affiliation: Department of Molecular Genetics, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen Groningen, Netherlands.
authors.forename: Oscar P
authors.initials: OP
authors.lastname: Kuipers
authors.affiliation: Laboratory of Microbiology, Department of Biology, Philipps-University Marburg Marburg, Germany.
authors.forename: Erhard
authors.initials: E
authors.lastname: Bremer
authors.affiliation: Space Microbiology Research Group, Radiation Biology Department, Institute of Aerospace Medicine, German Aerospace Center Cologne, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Moeller
keywords: B. subtilis spore germination; NaCl; RNA-seq; high salinity; osmotic stress; outgrowth; ripening