EVALUATION OF PETRIFILM SM FOR THE ENUMERATION OF THE AEROBIC FLORA OF FISH

Petrifilm™, developed by the 3M Laboratories, is a ready-touse system for enumerating bacteria. Dry media and a cold water soluble gel are coated on films, thus eliminating the need to prepare media. The enumerations obtained by this technique were compared to the results obtained by the conventional pour plate technique on 130 samples of flesh from whole whitings and 98 samples of fillets of white fish. For fish fillets, the counts obtained by the two methods were comparable. In the case of the flesh from whole fish, significantly higher results were obtained on Petrifilm (p<0.001). This difference was due to a luminous marine bacterium, Photobacterium phosphoreum, which grew on the Petrifilm plates, but not on PCA or PCA with 3.5% NaCl. Copyright © International Association of Milk, Food and Environmental Sanitarians.