Microbiological analysis of raw milk unveiled the presence of a dairy contaminant, Corynebacterium lipophiloflavum

Dairy farming occupied a distinct position in agriculture since milk can be harvested every day, providing a regular source of income to the farmers. Development of the Malaysian dairy farming industry was marred by poor farm hygiene practices, leading to the proliferation of dairy-spoilage bacteria, affecting milk quality. In this study, we report the isolation and characterization of a rare Corynebacterium species from raw milk after the implementation of improved farm hygiene practices. All milking equipment, farm worker’s hands and the cow’s udders and teats were washed with detergent and wiped dry with clean towels before milk sample collection. Collected foremilk samples from mastitis-free cows were inoculated onto Petrifilm™ and cultured colonies were plated onto nutrient agar. Biochemical and molecular tests were performed for the identification of peculiar bacterial isolates. A unique yellow-pigmented bacteria isolate was recovered from the milk of a healthy cow after the adoption of improved farm hygiene practices. Phenotypic and genotypic characterization confirmed the milk isolate as Corynebacterium lipophiloflavum. This is the first description of C. lipophiloflavum in cow’s milk and could possibly imply the influence of bovine flora in dairy contamination. The findings highlight the increasing spectrum of Corynebacterium species with potential adverse impact to the dairy industry. It is recommended to screen for C. lipophiloflavum in all milk processing facility to ensure that milk is safe for consumption and its products prepared to the highest quality and safety standards.