title: Genetic determinants of swarming in Rhizobium etli.
abstract: Swarming motility is considered to be a social phenomenon that enables groups of bacteria to move coordinately atop solid surfaces. The differentiated swarmer cell population is embedded in an extracellular slime layer, and the phenomenon has previously been linked with biofilm formation and virulence. The gram-negative nitrogen-fixing soil bacterium Rhizobium etli CNPAF512 was previously shown to display swarming behavior on soft agar plates. In a search for novel genetic determinants of swarming, a detailed analysis of the swarming behavior of 700 miniTn5 mutants of R. etli was performed. Twenty-four mutants defective in swarming or displaying abnormal swarming patterns were identified and could be divided into three groups based on their swarming pattern. Fourteen mutants were completely swarming deficient, five mutants showed an atypical swarming pattern with no completely smooth edge and local extrusions, and five mutants displayed an intermediate swarming phenotype. Sequence analysis of the targeted genes indicated that the mutants were likely affected in quorum-sensing, polysaccharide composition or export, motility, and amino acid and polyamines metabolism. Several of the identified mutants displayed a reduced symbiotic nitrogen fixation activity.
authors: Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001, Heverlee, Belgium.
authors: Kristien
authors: K
authors: Braeken
authors: Ruth
authors: R
authors: Daniels
authors: Karen
authors: K
authors: Vos
authors: Maarten
authors: M
authors: Fauvart
authors: Debkumari
authors: D
authors: Bachaspatimayum
authors: Jos
authors: J
authors: Vanderleyden
authors: Jan
authors: J
authors: Michiels
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004251:DNA Transposable Elements / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D009068:Movement; D009154:Mutation; D027805:Phaseolus / Q000382:microbiology; D053038:Quorum Sensing / Q000235:genetics; D042163:Rhizobium etli / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D013559:Symbiosis
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements