THE EFFECT OF RESUSCITATION AND THE INCUBATION-TEMPERATURE ON RECOVERY OF UNINJURED, HEAT INJURED AND FREEZE INJURED ENTEROCOCCI

Five strains of enterococci were inoculated on the Slanetz and Bartley enterococcus agar (EA), and incubated at 37-degrees-C and 44-degrees-C following: no injury, heat-injury and freeze-injury. The experiments were repeated introducing a 2 h resuscitation step in Tryptic Soy Agar (TSA) at 37-degrees-C and subsequent overlay with EA (TSA/EA) followed by incubation at both 37-degrees-C and 44-degrees-C. The TSA/EA method gave a significantly better recovery (1% confidence level) than the EA method at both 37-degrees-C and 44-degrees-C. The effect of incubation-temperature was only significant for two strains of Enterococcus durans, as one strain showed no growth at 44-degrees-C and the other strain was recovered significantly (5% confidence level) better at 37-degrees-C that at 44-degrees-C when employing the EA method. Interpretation of the results using TSA/EA method was easier than that of the EA. Different lactic streptococci and lactobacilli commonly employed in the dairy industry did not develop false positive colonies in TSA/EA incubated at 37-degrees-C.