Metagenomic Analysis of Raw Milk and the Inactivation of Foodborne Pathogens Using Ultraviolet-C

Abstract

The purpose of this study was to identify the microbial community of raw milk samples before and after UV-C irradiation and to establish fundamental data on UV-C treatment to improve the safety and shelf life of raw milk. Metagenomic analysis revealed that Lactococcus spp., Lactobacillus spp., and Staphylococcus spp. were the dominant genera in raw milk, while Pseudomonas spp. became more prevalent after 14 days of refrigerated storage. The microorganisms in raw milk were isolated using selective media and identified as Serratia quinivorans 4364 and Latilactobacillus curvatus DSM 20019. To compare the UV resistance of these microorganisms, Pseudomonas aeruginosa, Staphylococcus aureus, Lactococcus lactis, and Latilactobacillus curvatus were inoculated into sterilized milk and subjected to UV-C treatment. The reduction rates of P. aeruginosa were significantly lower than those of the other strains (S. aureus, L. lactis, and L. curvatus). These findings provide insights into the microbial distribution in raw milk and the degree of resistance to UV treatment, which can serve as fundamental data for the pasteurization of raw milk.