Na super(+) 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

• Published in: Archives of microbiology Vol. 187; no. 3; pp. 239 - 247
• Main Authors: Fujinami, Shun, Terahara, Naoya, Lee, Sunmi, Ito, Masahiro
• Format: Journal Article
• Language: English
• Published: 01.03.2007
• Subjects: Bacillus pseudofirmus
• ISSN: 0302-8933
• DOI: 10.1007/s00203-006-0192-7

Flagella-based motility of extremely alkaliphilic Bacillus species is completely dependent upon Na super(+). Little motility is observed at pH values < similar to 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 super(+), but significant motility at pH 7 at much higher Na super(+) concentrations. At pH 8-10, the swimming speed increased with the increase of Na super(+) 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.