Development of interspecific competition models for the growth of Listeria monocytogenes and Lactobacillus on vacuum-packaged chilled pork by quantitative real-time PCR.

The competitive growth of Listeria monocytogenes and Lactobacillus on vacuum-packaged chilled pork (VPCP) was studied by the use of Real-time PCR assay and selective culture counting method, where the Jameson-effect model and modified Lotka-Volterra model were chosen for the fitting of growth data. Real-time PCR assay was successfully applied to model the growth of the L.monocytogenes and Lactobacillus respectively on VPCP. The Jameson effect was occurred between L.monocytogenes and Lactobacillus when they co-existed in the same culture, and Lactobacillus clearly induced an early stationary phase of L. monocytogenes. The Jameson-effect model could be used to fit the growth curves of L. monocytogenes and Lactobacillus on VPCP. Thus the modified Lotka-Volterra competition model could be used to evaluate the interaction of two bacterial populations during the growth process, and found that the influence from Lactobacillus on L. monocytogenes was much higher than L. monocytogenes on Lactobacillus through the interaction coefficients. In conclusion, bacterial interactions need to be considered in microbial predictive models, which will provide a more practical assessment in predictive microbiology, and the model for the prediction based on the Real-time PCR assay can be used in future studies, especially for research of interaction models.