title: Na(+) and flagella-dependent swimming of alkaliphilic Bacillus pseudofirmus OF4: a basis for poor motility at low pH and enhancement in viscous media in an "up-motile" variant.
abstract: Flagella-based motility of extremely alkaliphilic Bacillus species is completely dependent upon Na(+). Little motility is observed at pH values < approximately 8.0. Here we examine the number of flagella/cell as a function of growth pH in the facultative alkaliphile Bacillus pseudofirmus OF4 and a derivative selected for increased motility on soft agar plates. Flagella were produced by both strains during growth in a pH range from 7.5 to 10.3. The number of flagella/cell and flagellin levels of cells were not strongly dependent on growth pH over this range in either strain although both of these parameters were higher in the up-motile strain. Assays of the swimming speed indicated no motility at pH < 8 with 10 mM Na(+), but significant motility at pH 7 at much higher Na(+) concentrations. At pH 8-10, the swimming speed increased with the increase of Na(+) concentration up to 230 mM, with fastest swimming at pH 10. Motility of the up-motile strain was greatly increased relative to wild-type on soft agar at alkaline pH but not in liquid except when polyvinylpyrrolidone was added to increase viscosity. The up-motile phenotype, with increased flagella/cell may support bundle formation that particularly enhances motility under a subset of conditions with specific challenges.
authors.affiliation: Graduate School of Life Sciences, Toyo University, 1-1-1 Izumino, Itakura-machi, Oura-gun, Gunma 374-0193, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Fujinami
authors.forename: Naoya
authors.initials: N
authors.lastname: Terahara
authors.forename: Sunmi
authors.initials: S
authors.lastname: Lee
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ito
mesh_terms: D000468:Alkalies / Q000494:pharmacology*; D001407:Bacillus / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D002465:Cell Movement; D002633:Chemotaxis; D003470:Culture Media; D005407:Flagella / Q000502:physiology*; D005408:Flagellin / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D012097:Repressor Proteins; D014783:Viscosity
chemical_list: D000468:Alkalies; D003470:Culture Media; D012097:Repressor Proteins; D005408:Flagellin