Serotyping and Genotyping Characterization of Pathogenic Escherichia coli Strains in Kimchi and Determination of Their Kinetic Behavior in Cabbage Kimchi During Fermentation

Abstract

This study determined the serotyping and genotyping properties of Escherichia coli strains isolated from kimchi and various raw vegetables used for kimchi preparation. In addition, the kinetic behavior of E. coli strains in kimchi during fermentation was also determined using a predictive microbiological model. The study results revealed that E. coli isolated from napa cabbage (3.3%; 1/30) was enterohemorrhagic E. coli (O6:H34), and eight typical colonies isolated from kimchi (15%; 6/40) were enteropathogenic E. coli (H8, H8, H12, H34, H30, O20:H39, H39, and H12). The genetic correlation of the strains did not show close genetic correlations. On the other hand, the kinetic behavior of E. coli strains in kimchi during fermentation using a predictive Baranyi model (primary model) and a polynomial equation (secondary model), followed by validation by calculating root mean square error (RMSE), revealed that the pathogenic E. coli cell counts increased (with RMSE of 0.280 in growth curve) in the early stage of fermentation and decreased (with RMSE of 0.920 in death curve) thereafter depending on fermentation temperature. Therefore, this finding indicated that pathogenic E. coli isolated from kimchi and related vegetables underwent proliferation at the beginning of fermentation, which decreased thereafter. Thus, these results of this study suggest intake of sufficiently fermented kimchi to prevent potential foodborne illness due to pathogenic E. coli.