title: Involvement of the Type IX Secretion System in Capnocytophaga ochracea Gliding Motility and Biofilm Formation.
abstract: Capnocytophaga ochracea is a Gram-negative, rod-shaped bacterium that demonstrates gliding motility when cultured on solid agar surfaces. C. ochracea possesses the ability to form biofilms; however, factors involved in biofilm formation by this bacterium are unclear. A type IX secretion system (T9SS) in Flavobacterium johnsoniae was shown to be involved in the transport of proteins (e.g., several adhesins) to the cell surface. Genes orthologous to those encoding T9SS proteins in F. johnsoniae have been identified in the genome of C. ochracea; therefore, the T9SS may be involved in biofilm formation by C. ochracea. Here we constructed three ortholog-deficient C. ochracea mutants lacking sprB (which encodes a gliding motility adhesin) or gldK or sprT (which encode T9SS proteins in F. johnsoniae). Gliding motility was lost in each mutant, suggesting that, in C. ochracea, the proteins encoded by sprB, gldK, and sprT are necessary for gliding motility, and SprB is transported to the cell surface by the T9SS. For the ΔgldK, ΔsprT, and ΔsprB strains, the amounts of crystal violet-associated biofilm, relative to wild-type values, were 49%, 34%, and 65%, respectively, at 48 h. Confocal laser scanning and scanning electron microscopy revealed that the biofilms formed by wild-type C. ochracea were denser and bacterial cells were closer together than in those formed by the mutant strains. Together, these results indicate that proteins exported by the T9SS are key elements of the gliding motility and biofilm formation of C. ochracea.
authors.affiliation: Department of Periodontology, Tokyo Dental College, Tokyo, Japan.
authors.forename: Daichi
authors.initials: D
authors.lastname: Kita
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Shibata
authors.affiliation: Department of Microbiology, Tokyo Dental College, Tokyo, Japan.|Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Kikuchi
authors.affiliation: Department of Microbiology, Tokyo Dental College, Tokyo, Japan.|Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.
authors.forename: Eitoyo
authors.initials: E
authors.lastname: Kokubu
authors.affiliation: Division of Microbiology and Oral Infection, Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Nakayama
authors.affiliation: Department of Periodontology, Tokyo Dental College, Tokyo, Japan.|Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Saito
authors.affiliation: Department of Microbiology, Tokyo Dental College, Tokyo, Japan ishihara@tdc.ac.jp.|Oral Health Science Center, Tokyo Dental College, Tokyo, Japan.
authors.forename: Kazuyuki
authors.identifier: http://orcid.org/0000-0002-6567-807X
authors.initials: K
authors.lastname: Ishihara
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D058947:Bacterial Secretion Systems / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D002206:Capnocytophaga / Q000235:genetics / Q000502:physiology*; D055786:Gene Knockout Techniques; D008124:Locomotion
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems