title: Virulent and nonvirulent Flavobacterium columnare colony morphologies: characterization of chondroitin AC lyase activity and adhesion to polystyrene.
abstract: OBJECTIVE
  Colony morphology variants of fish pathogenic Flavobacterium columnare were studied to clarify the role of colony morphology change in the virulence of the bacterium. Typical rhizoid colony (Rz) variants are virulent and moderately adherent, nonrhizoid rough (R) colony variants are nonvirulent and highly adherent, and soft colony (S) variants are nonvirulent and poorly adherent.
  
  
  RESULTS
  Chondroitin AC lyase activity, adhesion to polystyrene at different temperatures and after modification of bacterial surface, and lipopolysaccharide (LPS) profiles of the variants were studied. The chondroitinase activity was significantly higher in the virulent, rhizoid variants than in the rough variants of the same strain. Temperature significantly increased the adhesion of rhizoid variants up to 20°C. Modification of bacterial surface suggested that adhesion molecules contain both carbohydrates and proteins. LPS did not differ between the variants of the same strain.
  
  
  CONCLUSIONS
  The results suggest that in Fl. columnare both rhizoid colony morphology and high chondroitinase activity are needed for virulence and that temperature may promote the adhesion of the virulent variants to surfaces at fish farms.
  
  
  CONCLUSIONS
  New information is produced on the virulence mechanisms of Fl. columnare and the reasons behind the survival of the bacterium at fish farms.
authors.affiliation: Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland. heidi.m.t.kunttu@jyu.fi
authors.forename: H M T
authors.initials: HM
authors.lastname: Kunttu
authors.forename: E I
authors.initials: EI
authors.lastname: Jokinen
authors.forename: E T
authors.initials: ET
authors.lastname: Valtonen
authors.forename: L-R
authors.initials: LR
authors.lastname: Sundberg
mesh_terms: D000818:Animals; D001422:Bacterial Adhesion; D002808:Chondroitin Lyases / Q000378:metabolism*; D005393:Fish Diseases / Q000382:microbiology; D005399:Fishes / Q000382:microbiology; D005417:Flavobacterium / Q000166:cytology / Q000201:enzymology* / Q000472:pathogenicity; D008070:Lipopolysaccharides / Q000032:analysis; D011137:Polystyrenes; D013696:Temperature; D014774:Virulence
chemical_list: D008070:Lipopolysaccharides; D011137:Polystyrenes; D002808:Chondroitin Lyases