Incidence of motile aeromonads in marine environment, fishes and processed fishery products

Abstract

Motile Aeromonds ubiquitous to the aquatic environment has been frequently associated with disease of fishes and other aquatic animals. Recent studies point to its role as a causative agent for foodborne gastroenteritis. This paper reports the incidence of motile aeromonds in the fishing ground, raw marine fish and processed fishery products. The density of motile aeromonad in the samples were analyzed by direct plating and enrichment methods along with a total plate count. Typical isolates were identified upto species level. In sea water of the fishing grounds off Cochin, the aeromonad count ranged between 4.0 * 10^2 to 2.1 * 10^3 /ml in July-August. The aeromonad count in the skin with muscle of the fishes during that period were in the range of 9 * 10^2/g to 9.9 * 10^5/g corresponding to a TPC range of 6.7 * 10^4/g to 7.12 * 1066/g. In frozen fishes the aeromonad count ranged between 9.0/g to 2.0 * 10^4/g and the TPC, in the range of 4.5 * 1064/g to 9.7 * 10^5/g. Cured of salted fishes were found to be free from motile aeromonads. Random colonies picked from the plate were identified upto species level and the dominant species in water, raw fish and frozen fish were found to A. caviae which is considerd as non-toxigenic. the incidence of Aeromonas hydrophila was more in the frozen fish than fresh fish. the enterotoxigencity of the isolates were assessed on the basis of biochemical tests.