SURVIVAL OF PSYCHROTROPHIC VIBRIO-MIMICUS, VIBRIO-FLUVALIS AND VIBRIO-PARAHAEMOLYTICUS IN CULTURE BROTH AT LOW-TEMPERATURES

Pathogenic vibrios are important etiologic agents in tropical regions and have been frequently recovered from seafoods and aquacultured foods. A number of psychrotrophic vibrios were isolated and selected from frozen seafoods and their survivals in tryptic soy broth (TSB) at 4-degrees-C and -30-degrees-C were studied. These psychrotrophic strains showed good survival at low temperatures and could probably enhance the risk of vibrios in frozen foods. Vibrio mimicus 70 and 198, Vibrio fluvialis 52 and Vibrio parahaemolyticus 205 survived well at 10-degrees-C, 4-degrees-C and -30-degrees-C, while the non-cold fitter V. fluvialis 28 was completely inactivated in the test periods. These strains were not heat resistant and could be easily inactivated by heat treatment. Effect of phosphates may be different for various Vibrio species at low temperatures. Survival of V. parahaemolyticus 205 was significantly protected by the heated metaphosphate at 4-degrees-C by lowering the lethality of cold injured cells but not by increasing the level of uninjured viable cells. Pyrophosphate was inhibitory to this V parahaemolyticus strain at -30-degrees-C.