Survival of Challenging Food˗borne Pathogens of Dairy Origin in Milk Inoculated with Lactic Acid Bacteria as Co-Culture: Implication for Food Safety

Abstract

Understanding interaction of foodborne pathogens such as Escherichia coli, and Staphylococcus aureus in milk is pivotal due to high cases of foodborne infection. This study evaluated the survival of food-borne pathogen in milk and the potential of lactic acid bacteria as co-culture in modulating foodborne pathogen behavior. The milk sample were collected from four locations which include University of Ibadan Research Farm, Bodija cattle market, Akinyele cattle market and Sabo cattle market in Ibadan, Oyo State, Nigeria. Isolation, identification and total count of the pathogens from the milk were evaluated using plate count. Pathogen count of all milk samples exceeded the zero count which is the World Health Organization limit. Pathogens isolated includes Staphylococcus aureus, Escherichia coli, Salmonella typhimurium, Shigella dysentriae, Enterobacter cloacae and Serratia marcescens. Again, Lactococcus lactis, Lactiplantibacillus plantarum and Lactobacillus delbrueckii subsp. bulgaricus previously isolated from raw milk and identified using API kits acts as co-culture. All data were subjected to ANOVA and treatment means separated. There were significant variation in bacterial count across different dairy farms with the highest total bacterial count consistently observed in samples from Sabo cow market (SB). Mean count ranged from 1.70 ± 0.1 to 3.10 ± 0.1 (106 CFU/mL). The impact of Lactic acid bacteria on the survival of six food-borne pathogens in milk were assessed over 24-hours. A decreasing trend in bacterial count was observed across all pathogens, with statistically significant reductions (p < 0.05) in CFU/mL for each organism. Conclusively, the findings revealed that lactic acid bacteria co-cultured with food pathogens could reduce the survival of the pathogens in milk especially in areas or settings without reliable pasteurization and refrigeration. Hence emphasizing potential role in bio-preservation and also improving food biotechnology.