title: The chemotaxis-like Che1 pathway has an indirect role in adhesive cell properties of Azospirillum brasilense.
abstract: The Azospirillum brasilense chemotaxis-like Che1 signal transduction pathway was recently shown to modulate changes in adhesive cell surface properties that, in turn, affect cell-to-cell aggregation and flocculation behaviors rather than flagellar-mediated chemotaxis. Attachment to surfaces and root colonization may be functions related to flocculation. Here, the conditions under which A. brasilense wild-type Sp7 and che1 mutant strains attach to abiotic and biotic surfaces were examined using in vitro attachment and biofilm assays combined with atomic force microscopy and confocal microscopy. The nitrogen source available for growth is found to be a major modulator of surface attachment by A. brasilense and could be promoted in vitro by lectins, suggesting that it depends on interaction with surface-exposed residues within the extracellular matrix of cells. However, Che1-dependent signaling is shown to contribute indirectly to surface attachment, indicating that distinct mechanisms are likely underlying flocculation and attachment to surfaces in A. brasilense.
authors.affiliation: Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
authors.forename: Piro
authors.initials: P
authors.lastname: Siuti
authors.forename: Calvin
authors.initials: C
authors.lastname: Green
authors.forename: Amanda Nicole
authors.initials: AN
authors.lastname: Edwards
authors.forename: Mitchel J
authors.initials: MJ
authors.lastname: Doktycz
authors.forename: Gladys
authors.initials: G
authors.lastname: Alexandre
mesh_terms: D015806:Azospirillum brasilense / Q000378:metabolism / Q000502:physiology*; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development; D002633:Chemotaxis; D037102:Lectins / Q000378:metabolism; D018625:Microscopy, Atomic Force; D018613:Microscopy, Confocal; D009584:Nitrogen / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D037102:Lectins; D009584:Nitrogen