title: Genome-wide transcriptional profiling analysis of adaptation of Bacillus subtilis to high salinity.
abstract: The gram-positive soil bacterium Bacillus subtilis often faces increases in the salinity in its natural habitats. A transcriptional profiling approach was utilized to investigate both the initial reaction to a sudden increase in salinity elicited by the addition of 0.4 M NaCl and the cellular adaptation reactions to prolonged growth at high salinity (1.2 M NaCl). Following salt shock, a sigB mutant displayed immediate and transient induction and repression of 75 and 51 genes, respectively. Continuous propagation of this strain in the presence of 1.2 M NaCl triggered the induction of 123 genes and led to the repression of 101 genes. In summary, our studies revealed (i) an immediate and transient induction of the SigW regulon following salt shock, (ii) a role of the DegS/DegU two-component system in sensing high salinity, (iii) a high-salinity-mediated iron limitation, and (iv) a repression of chemotaxis and motility genes by high salinity, causing severe impairment of the swarming capability of B. subtilis cells. Initial adaptation to salt shock and continuous growth at high salinity share only a limited set of induced and repressed genes. This finding strongly suggests that these two phases of adaptation require distinctively different physiological adaptation reactions by the B. subtilis cell. The large portion of genes with unassigned functions among the high-salinity-induced or -repressed genes demonstrates that major aspects of the cellular adaptation of B. subtilis to high salinity are unexplored so far.
authors.affiliation: Department of Biology, Laboratory for Microbiology, Philipps-University Marburg, D-35032 Marburg, Germany.
authors.forename: Leif
authors.initials: L
authors.lastname: Steil
authors.forename: Tamara
authors.initials: T
authors.lastname: Hoffmann
authors.forename: Ina
authors.initials: I
authors.lastname: Budde
authors.forename: Uwe
authors.initials: U
authors.lastname: Völker
authors.forename: Erhard
authors.initials: E
authors.lastname: Bremer
mesh_terms: D000222:Adaptation, Physiological; D001412:Bacillus subtilis / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D003470:Culture Media; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D006360:Heat-Shock Proteins / Q000235:genetics; D007501:Iron / Q000494:pharmacology; D009068:Movement; D020411:Oligonucleotide Array Sequence Analysis; D012343:RNA, Transfer / Q000235:genetics; D018085:Regulon; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology*
chemical_list: D001426:Bacterial Proteins; D003470:Culture Media; C066496:DegS protein, Bacteria; C066497:DegU protein, Bacteria; D006360:Heat-Shock Proteins; C079011:SigB protein, Bacteria; C413458:SigW protein, Bacillus subtilis; D012808:Sigma Factor; D012965:Sodium Chloride; D012343:RNA, Transfer; D007501:Iron