Inter-Research > DAO > v93 > n3 > p207-214  
Diseases of Aquatic Organisms

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DAO 93:207-214 (2011)  -  DOI:

Serological and molecular heterogeneity among Yersinia ruckeri strains isolated from farmed Atlantic salmon Salmo salar in Chile

A. Bastardo1,2, H. Bohle3, C. Ravelo2, A. E. Toranzo1, J. L. Romalde1,*

1Departamento de Microbiología y Parasitología, CIBUS, Universidad de Santiago de Compostela, 15782 Spain
2Estación de Investigaciones Hidrobiológicas de Guayana, Fundación La Salle de Ciencias Naturales, 8051 Venezuela
3ADL Diagnostic Chile Ltd, Puerto Montt, 5480000 Chile
*Corresponding author. Email:

ABSTRACT: We investigated 11 strains of Yersinia ruckeri, the causative agent of enteric redmouth disease (ERM), that had been isolated from Atlantic salmon Salmo salar L. farmed in Chile and previously vaccinated against ERM. Phylogenetic analysis of the 16S rRNA gene sequences confirmed the identification of the salmon isolates as Y. ruckeri. A comparative analysis of the biochemical characteristics was made by means of traditional and commercial miniaturised methods. All studied isolates were motile and Tween 80 positive, and were identified as biotype 1. In addition, drug susceptibility tests determined high sensitivity to sulphamethoxazole/trimethroprim, oxytetracycline, ampicillin and enrofloxacin in all isolates. Serological assays showed the presence of O1a, O1b and O2b serotypes, with a predominance of the O1b serotype in 9 strains. Analysis of the lipopolysaccharide profiles and the correspondent immunoblot confirmed these results. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of the outer membrane proteins revealed that all Chilean strains had profiles with a molecular weight range between 34 and 55 kDa, with 3 distinct groups based on differences in the major bands. Genotyping analyses by enterobacterial repetitive intergenic consensus (ERIC-) and repetitive extragenic palindromic (REP-)PCR techniques clearly indicated intraspecific genetic diversity among Chilean Y. ruckeri strains.

KEY WORDS: Yersinia ruckeri · Enteric redmouth disease · ERM · Atlantic salmon · Serology · Outer membrane proteins · Lipopolysaccharide · Genotyping

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Cite this article as: Bastardo A, Bohle H, Ravelo C, Toranzo AE, Romalde JL (2011) Serological and molecular heterogeneity among Yersinia ruckeri strains isolated from farmed Atlantic salmon Salmo salar in Chile. Dis Aquat Org 93:207-214.

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