Effect of Temperature Shock on Pediococcus Acidilactici: Viability and Molecular Study

Abstract

Probiotics are microorganisms that can confer health benefits when consumed in sufficient amounts. One of the examples of probiotics is Pediococcus acidilactici which has probiotic potential due to its characteristics, such as its ability to produce pediocin. Probiotics are usually subjected to various temperature stresses during their processing and storage, which may lead to undesirable loss of viability of probiotics. There has been little research about the effect of temperature shock on Pediococcus acidilactici, especially its molecular responses. This study aims to investigate the effect of various temperature shocks on the viability and stress-related gene expression of Pediococcus acidilactici. The study was conducted by investigating the viability of P.acidilactici after temperature shock of -80°C, 4°C, 60°C, 75°C, and 90°C for 5 minutes with 30°C as the control. Gene expression analysis by RT-qPCR was also conducted to see the expression of the groEL gene in selected temperature shock treatment, using Ldh as a reference gene. Overall, there was no significant reduction of viability of P. acidilactici after temperature shock for 5 minutes at -80°C, 4°C, and 60°C in comparison to 30°C (Log 9.2-9.3 CFU/mL), while there was significant reduction to the culture subjected to 75°C for (Log 6.17) and 90°C for (0). Gene expression analysis indicated no significant differences in groEL gene expression of culture subjected to -80°C, 4°C, and 60°C in comparison to control of 30°C, although the validity of the result is in question due to several possible problems, mainly gDNA contamination.