Molecular typing by pulsed‐field gel electrophoresis of Flavobacterium psychrophilum isolates derived from Japanese fish

Abstract

Sixty-four isolates of Flavobacterium psychrophilum from ayu, Plecoglossus altivelis altivelis (Temminck & Schlegel), and other fish (n=16) in Japan and the type strain (NCIMB 1947(T)) were typed using pulsed-field gel electrophoresis (PFGE) with endonuclease BlnI and XhoI. These isolates were classified into 20 clusters and 42 genotypes by PFGE analysis. The most predominant cluster of isolates from ayu was cluster XII (n=20), followed by clusters XVII, XVI, XX, XI, IX, X, XIII and XV; the remaining 17 isolates from other fish were divided into clusters I, II, III, IV, V, VI, VII, VIII, XIV, XVIII and XIX. The PFGE genotype of isolates from ayu clearly differed from those of other fish. The isolates from ayu in Gunma Prefecture belonged to clusters XII, XVI, XVII and XX, and the strains of three of these clusters (XII, XVII and XX) were isolated from ayu in 15 of 19 prefectures. PFGE typing enabled more accurate classification of isolates into clusters than previously achieved by analysing the restriction fragment length polymorphism of PCR products. These results suggest that F. psychrophilum isolated from ayu and other fish are genetically different and strains with several PFGE types have spread within Japan.

Biochemical and molecular heterogeneity among isolates of Yersinia ruckeri from rainbow trout (Oncorhynchus mykiss, Walbaum) in north west Germany

“…PFGE has been frequently applied for detailed molecular typing of different bacteria [37-39], as well as for a differentiation among isolates of Y. ruckeri [15]. In the present study, the typing results by PFGE showed strong homogeneity among the isolates obtained from farmed fish species in north west Germany.…”

Infection Status of Ayu and Other Wild Fish with <i>Flavobacterium psychrophilum</i> and <i>Edwardsiella ictaluri</i> in the Tama River, Japan

“…Since the genotype A isolate is considered to be associated with specific pathogenicity against ayu in most cases (Izumi et al, 2003;Yoshiura et al, 2006), the other fish species are unlikely to be the source of F. psychrophilum infection of riverine ayu in the present survey sites. On the other hand, past studies suggest that the release of asymptomatic carrier ayu with F. psychrophilum resulted in BCWD (Inouye, 2000;Arai et al, 2007;Kumagai et al, 2010). In the present survey, we did not detect F. psychrophilum in seed-production ayu released at St. D, but we found positive fish for the bacterium from ayu released at Stn.…”

Comparative analysis and mutation effects of fpp2–fpp1 tandem genes encoding proteolytic extracellular enzymes of Flavobacterium psychrophilum

“…The disease mainly affects fingerlings, and is currently considered one of the most significant bacterial infections in the salmonid industry, causing high mortality and serious economic losses worldwide. Although F. psychrophilum is considered a rather fastidious bacterium because it is difficult to isolate and handle (Michel et al, 1999), significant advances have been made over the last few years in culture (Michel et al, 1999;Cepeda et al, 2004;Á lvarez & Guijarro, 2007), typing (Izumi et al, 2003;Soule et al, 2005;Arai et al, 2007;Nicolas et al, 2008), molecular diagnosis Cepeda & Santos, 2000;del Cerro et al, 2002;Fujiwara-Nagata & Eguchi, 2009) and genomics (Duchaud et al, 2007). Moreover, a genetic manipulation system based on conjugation, transformation and transposon mutagenesis has been developed (Á lvarez et al, 2004).…”