Comparative study on spoilage and pathogenic bacteria in selected commercial marine and freshwater fishes

Abstract

Microorganisms are the major cause of spoilage of most seafood products. Fishes are more
\nperishable than other protein foods and thus more prone to bacterial contamination. Based on
\nabove perspectives, a bacterial invasion in commercially important fresh and spoiled marine
\n(Lates calcarifer, Lutjanus sanguineus) and freshwater fish (Pangasius pangasius) were
\nanalyzed using API 20E kit. Out of 25 isolates obtained from fresh water fish, only 6 isolates were
\ncharacterized as Gram-positive bacteria and the rest were Gram negative strains (19 isolates).
\nThe most dominant genera were Vibrio, Enterobacter, Serratia, and Aeromonas. All these
\nbacteria were found in both fresh fish and spoiled fish sample while Erwinia spp. and Kluyvera
\nspp. were identified only in fresh fish samples. Out of four (4) strains of Staphylococcus spp.,
\nS. xylosus was detected exclusively from spoiled fish. The higher number of bacterial micro
\nflora in the spoiled fish gut indirectly indicated increased microbial degradation in the fish
\ngut during spoilage process. Notably, almost all the isolates were lactose degraders, positive
\noxidizers and carbohydrate fermenters. Vibrio fluvialis, Proteus mirabilis, Proteus vulgaris,
\nBrucella sp. and Ochrabactrum anthropi were the human pathogenic bacteria found in marine
\nfish Lates calcarifer (Sea perch). While Vibrio fluvialis, Proteus mirabilis and Proteus vulgaris
\nwere detected in Lutjanus sanguineus (Red snapper). The study portrays that the existing postharvest
\nhandling techniques could be a vital factor for degrading hygienic conditions of fish in
\nlocal fish markets. Nevertheless, a long term monitoring is an urgently needed for sustaining
\nthe quality flesh of fish towards the betterment of the consumer’s health.