Influence of Potassium Sorbate on the Growth of Yersinia enterocolitica

The growth and survival of Yersinia enterocolitica 0:3 and 0:8 were determined using Brain Heart Infusion Broth at pH 5.5 or 6.5, with 0, 250, 500, 1000, 1500, 2500, or 5000 ppm potassium sorbate, and incubated at 25 or 3°C. Results showed that Y. enterocolitica was susceptible to the antimicrobial activity of potassium sorbate. At 25°C and pH 5.5, a population increase of 6.8 and 6.9 log CFU/ml was noted for Y. enterocolitica serotypes 0:3 and 0:8, respectively, in broth without potassium sorbate. The presence of 1000-1500 ppm potassium sorbate in broth retarded the growth of the inoculated Y. enterocolitica cells or partially or completely inactivated them. At 25°C and pH 6.5, potassium sorbate at a concentration as high as 5000 ppm did not inactivate this pathogen. All the concentrations of potassium sorbate tested only retarded the growth of Y. enterocolitica . A 3°C and pH 5.5, Y. enterocolitica grew slightly in the control broth. The presence of 250-500 ppm or more potassium sorbate in broth completely inhibited the growth of Y. enterocolitica or reduced the number of viable cells. At 3°C and pH 6.5, a slight increase in the population of Y. enterocolitica was observed in the broth with or without potassium sorbate, but the increase slacked off as the amount of potassium sorbate was increased.