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 by Pseudomonas putrefaciens, a "non-defined" group resembling Ps. putrefaciens, Photobacterium spp. and some Moraxella-like bacteria. Hypoxanthine is produced by the same groups of bacteria except the last named and also by the "typical shrimp spoilers" (presumptive Alteromonas). Strong off-odours are produced on fresh fish by Ps. putrefaciens, dextrose-oxidative Pseudomonas spp. (Groups I and II according to Shewan, Hobbs and Hodgkiss, 1960), the above mentioned "non-defined" group and by only some of the "typical shrimp spoilers", whereas Moraxella-like bacteria and Photobacterium spp. failed to produce strong odours. Strong off-odours are produced on boiled shrimp by the "typical shrimp spoilers" (presumptive Altermonas). Ps. putrefaciens, the dextrose-oxidative Pseudomonas spp. and the "non-defined" group; Moraxella-like bacteria produced less offensive odours or none, nor did Photobacterium.