Vibriosis in some fishes: molecular characterization of fish pathogenic vibrios

ABSTRACT

Studies were undertaken to isolate and characterize vibrio species pathogenic to fish. Thirty six vibrio-like isolates were obtained from twenty one of 160 fish samples. Biochemically the collected isolates were identified as Listonella anguillarum biotype B and C, Vibrio alginolyticus and unidentified lactose-fermenting vibrio spp. Eight vibrio strains of different origins were selected and were grown onto tryptose soya agar with 5% sheep blood for preparation of outer membrane proteins [OMPs]. The OMP profiles of the tested strains were separated using sodium dodecyl- sulphate polyacrylamide gel electrophoresis [SDS- PAGE]. Dice index of similarity was determined with each strain. Analysis of OMPs showed that the local vibrio strains had 8-9 protein bands of molecular weight ranging from 19.7- 212.9 KDa and they contained three major protein bands of molecular weight 19.7, 36 and 80 KDa. Moreover, SDS - PAGE analysis of the local vibrio strains indicated OMP expression differences in protein between strains defined mutant and within the same species strains belonging to different biogroups possessed distinct electrophoretic banding proteins. In conclusion SDS-PAGE analysis of OMPs may be considered as sensitive, reliable and rapid diagnostic method to characterize vibrio isolates