title: Swarming motility in Bradyrhizobium japonicum.
abstract: Flagellar-driven bacterial motility is an important trait for colonization of natural environments. Bradyrhizobium japonicum is a soil species that possesses two different flagellar systems: one subpolar and the other lateral, each with a filament formed by a different set of flagellins. While synthesis of subpolar flagellins is constitutive, translation of lateral flagellins was detected in rhizobia grown with l-arabinose, but not with d-mannitol as sole carbon source, independently of whether bacteria were in liquid or semisolid medium. We characterized swarming of B. japonicum in semisolid medium and found that this motility was faster with l-arabinose than with d-mannitol. By using mutants with deletions in each flagellin set, we evaluated the contribution of each flagellum system to swarming in semisolid culture media, and in soil. Mutants devoid of either of the flagella were affected in swarming in culture media, with this impairment being stronger for mutants without lateral flagella. In sterile soil at 100% or 80% field capacity, flagellar-driven motility of mutants able to swim but impaired in swarming was similar to wild type, indicating that swimming was the predominant movement here.
authors.affiliation: Instituto de Biotecnología y Biología Molecular (IBBM), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata y CCT La Plata-CONICET, Calles 47 y 115, 1900 La Plata, Argentina. jcovelli@biol.unlp.edu.ar
authors.forename: Julieta Mariana
authors.initials: JM
authors.lastname: Covelli
authors.forename: María Julia
authors.initials: MJ
authors.lastname: Althabegoiti
authors.forename: María Florencia
authors.initials: MF
authors.lastname: López
authors.forename: Aníbal Roberto
authors.initials: AR
authors.lastname: Lodeiro
mesh_terms: D001089:Arabinose / Q000378:metabolism; D020369:Bradyrhizobium / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D003470:Culture Media / Q000737:chemistry; D005407:Flagella / Q000502:physiology; D005408:Flagellin / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008124:Locomotion; D008353:Mannitol / Q000378:metabolism; D012988:Soil Microbiology
chemical_list: D003470:Culture Media; D005408:Flagellin; D008353:Mannitol; D001089:Arabinose