Characterization of some fish and shrimp spoiling bacteria

The classification of some important groups of bacteria involved in fish and shrimp spoilage was studied. Trimethylamine is produced byPseudomonas putrefaciens, a “non-defined” group resemblingPs. putrefaciens, Photobacterium spp. and someMoraxella-like bacteria. Hypoxanthine is produced by the same groups of bacteria except the last named and also by the “typical shrimp spoilers” (presumptiveAlteromonas). Strong off-odours are produced on fresh fish byPs. putrefaciens, dextroseoxidativePseudomonas spp. (Groups I and 11 according to Shewan, Hobbs and Hodgkiss, 1960), the above mentioned “non-defined” group and by only some of the “typical shrimp spoilers”, whereasMoraxella-like bacteria andPhotobacterium spp. failed to produce strong odours. Strong off-odours are produced on boiled shrimp by the “typical shrimp spoilers” (presumptiveAltermonas),Ps. putrefaciens, the dextrose-oxidativePseudomonas spp. and the “non-defined” group;Moraxella-like bacteria produced less offensive odours or none, nor didPhotobacterium.