title: EPS II-dependent autoaggregation of Sinorhizobium meliloti planktonic cells.
abstract: Planktonic cells of Sinorhizobium meliloti, a Gram-negative symbiotic bacterium, display autoaggregation under static conditions. ExpR is a LuxR-type regulator that controls many functions in S. meliloti, including synthesis of two exopolysaccharides, EPS I (succinoglycan) and EPS II (galactoglucan). Since exopolysaccharides are important for bacterial attachment, we studied the involvement of EPS I and II in autoaggregation of S. meliloti. Presence of an intact copy of the expR locus was shown to be necessary for autoaggregation. A mutant incapable of producing EPS I displayed autoaggregation percentage similar to that of parental strain, whereas autoaggregation was significantly lower for a mutant defective in biosynthesis of EPS II. Our findings clearly indicate that EPS II is the essential component involved in autoaggregation of planktonic S. meliloti cells, and that EPS I plays no role in such aggregation.
authors.affiliation: Departamento de Biología Molecular, Universidad Nacional de Río Cuarto, Río Cuarto, Córdoba, Argentina.
authors.forename: Fernando G
authors.initials: FG
authors.lastname: Sorroche
authors.forename: Luciana V
authors.initials: LV
authors.lastname: Rinaudi
authors.forename: Angeles
authors.initials: A
authors.lastname: Zorreguieta
authors.forename: Walter
authors.initials: W
authors.lastname: Giordano
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D018533:Biomass; D005427:Flocculation; D005685:Galactans; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005936:Glucans / Q000502:physiology*; D056265:Microbial Interactions; D011135:Polysaccharides, Bacterial / Q000502:physiology*; D053038:Quorum Sensing; D016962:Sinorhizobium meliloti / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D013559:Symbiosis / Q000235:genetics
chemical_list: D005685:Galactans; D005936:Glucans; D011135:Polysaccharides, Bacterial; C093768:galactoglucan; C056779:succinoglycan
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