Autoagglutination, growth on tryptone‐soy‐Coomassieagar, outer membrane protein patterns and virulence of <i>Aeromonas salmonicida</i> strains

Abstract

Abstract. Twelve Aeromonas salmonicida isolates were examined for autoagglutination, colony colour on tryptone soy agar supplemented with Coomassie brilliant blue (TSA‐C), and outer membrane protein pattern by sodium dodecyl sulphate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Autoagglutination did not correlate with colony colour on TSA‐C, nor with the presence of the additional 49‐kDa protein (A‐protein) in all strains tested. However, there was a correlation between colour on TSA‐C and A‐protein. Two weakly autoagglutinating isolates with no A‐protein detectable in SDS‐PAGE and with negative staining behaviour on TSA‐C shared another additional protein, designated X‐protein. One of these isolates was virulent for juvenile rainbow trout, the other one avirulent. Thus, for the strains examined, neither autoagglutination nor X‐protein were reliable indicators of virulence, and absence of A‐protein did not necessarily mean avirulence.