Genetic diversity of North American isolates of Renibacterium salmoninarum

Abstract

Genetic diversity of Renibacterium salmoninarum was evaluated by multilocus enzyme electrophoresis (MEE). Whole cell lysates were prepared for 40 isolates representing 5 groups based on host and geographic area. Each lysate was assessed for activity of 44 enzymes with a pH 6.5 amine-citrate and a pH 8.0 buffer. Genetic variation was scored at 26 loci. Two zones of activity (presumptive loci) were scored each for esterase (EC 3.1.1.1) and glycyl-leucine peptidase (EC 3.4.11.x). There were no monomorphic loci and there was an average of 2.65 electromorphs per locus. There were 21 electrophoretic types. Mean genetic diversity (H(T)) was 0.161 and the percentage of this explained by diversity between groups was G(st) = 8.1%; thus 91.9% of the genetic diversity was due to heterogeneity between individual isolates. The 2 groups with the highest genetic diversity were from chinook Oncorhynchus tshawytscha and coho O. kisutch salmon, both from the Manistee Weir, Michigan, USA; i.e. 0.270 and 0.298, respectively. The highest genetic diversity for a locus (h(T)) was 0.587 for EST-1. At this locus, diversity between groups explained a higher percentage of the total diversity (G(st) = 36.5%). Other loci with relatively high genetic diversity were succinate dehydrogenase (0.385; EC 1.3.99.1), cytochrome c oxidase (0.273; EC 1.9.3.1) and aconitase (0.3111; EC 4.2.1.3). The results of this study indicate relatively low genetic diversity of R. salmoninarum.