Bio-preservation of meat against pathogens using probiotics and their associated metabolites

Abstract

Microbial contamination on food can results in foodborne illnesses and food spoilage, which can relate to food safety and food security in a global scale respectively. Escherichia coli O157:H7 and Pseudomonas spp. play their roles in foodborne illnesses and spoilage respectively in food system. Food preservation is a counter for microbial contamination. Probiotic and their associated metabolites are used as a potential counter in food preservation. Freeze-drying technology is another food preservation method in the food industry. This project aims to identify effective probiotic strains and their metabolites that have antimicrobial activity against microbial pathogens, specifically Escherichia coli O157:H7 and Pseudomonas spp. The methods used include agar diffusion assays on nutrient agar and skim milk agar to screen the probiotic strains for antimicrobial effects against the microbial pathogens. Lactiplantibacillus plantarum PCB019 was found to be the most effective probiotic strain with strong antimicrobial activity, followed by Lacticaseibacillus rhamnoses GG and L. plantarum PCB011. Small bacterial colonies were occasionally observed within the inhibition zone, suggests the possible presence of suppressor mutants. L. plantarum PCB019 overnight culture and CFS had the higher inhibition measurement than LGG overnight culture and CFS for the second screening. L. plantarum PCB019 and L. paracasei PCB002 in CFS and freeze-dried form had no antimicrobial activity on skim milk agar. The FTIR analysis was a preliminary trial to evaluate bioactive metabolites and found that FD LGG exhibiting the most diverse metabolite signature that could be attributed to the antimicrobial activity. The results were not conclusive as not all the samples were assessed, and more detailed techniques are required to gather more information.