Effects of Temperature Shock on Viability and Stress-Related Gene Expression in Pediococcus acidilactici, a Probiotic Lactic Acid Bacteria

Abstract

Abstract Probiotics are live microorganisms that can confer health benefits when consumed in sufficient amounts. However, probiotics are often subjected to various temperature stresses during their processing and storage, which may lead to undesirable loss of viability. Pediococcus acidilactici, a species of lactic acid bacteria, is a promising probiotic candidate due to its ability to produce the antimicrobial peptide pediocin. Their response to temperature-related stress, especially at the molecular level, is still poorly understood. This study investigated the effect of shocks at various temperatures on the viability and stress-related gene expression of P. acidilactici. There was no significant reduction in the viability of P. acidilactici after temperature shock for 5 minutes at -80°C, 4°C, and 60°C compared to the control at 30°C (Log 9.2-9.3 CFU/mL), while there was a significant reduction in the culture subjected to 75°C (Log 6.17) and 90°C (0), both for 5 mins. RT-qPCR analysis showed no significant differences in the expression of groEL, a heat shock response gene, in P. acidilactici subjected to -80°C, 4°C, and 60°C compared to 30°C, although possible gDNA contamination might occur. These results suggest that P. acidilactici potentially has good survival when subjected to heat-based food processing for probiotics product development.