ABSTRACT: Total genomic DNA samples of atypical isolates of Aeromonas salmonicida from goldfish Carassius auratus L., silver perch Bidyanus bidyanus (Mitchell), and greenback flounder Rhombosolea tapirina Günther from Australia and isolates from goldfish from the USA and Singapore were digested with the restriction enzyme CfoI, separated in 3.5% acrylamide gels and visualised by silver staining. Isolates from goldfish and silver perch comprised an homogenous group while those from greenback flounder formed a second group. Within the goldfish and silver perch isolates there were minor differences in restriction endonuclease fragment pattern. Isolates from Australian goldfish obtained between 1977 and 1989 were indistinguishable from isolates from goldfish from the USA but slightly different from an isolate from a Singaporean goldfish. These and other data suggest that A. salmonicida probably crossed a species barrier from goldfish to silver perch on the same farm but that farmed greenback flounder in Tasmania have acquired a distinct strain of A. salmonicida probably from wild-caught marine fish.

KEY WORDS: Atypical Aeromonas salmonicida . DNAanalysis . Molecular epidemiology . Carassius auratus . Bidyanus bidyanus . Rhombosolea tapirina . Australia

Published in DAO Vol. 22, No. 3 (1995) on July 13
ISSN: 0177-5103. Copyright © Inter-Research, Oldendorf/Luhe, 1995