Shelf-Life Storage Conditions Dependent Anti-S. Aureus Efficacy of Live and Attenuated Lactobacillus Rhamnosus: An in Vitro Study

Abstract

Introduction: The effect of different storage condition and duration on probiotic viability, cell membrane compositional characteristics, and its antibacterial efficacy is not well studied.

Objectives: The present study evaluated the impact of different storage conditions on the viability, membrane characteristics, and antibacterial effect of live and heat attenuated Lactobacillus rhamnosus at various shelf life stages.

Methods: Live and heat attenuated L. rhamnosus probiotic was prepared and stored at -20°C, 2-8°C, 25°C ± 60% RH, and 40°C ± 75% RH for 12 months. Representative samples from each storage condition at baseline, months 3, 6, and 12 were utilized for evaluating viability, intactness, and antibacterial efficacy using in vitro Staphylococcus aureus growth inhibition method.

Results: Progressive reduction in the viability and number of intact cells of live and attenuated L. rhamnosus was observed. After 12 months, probiotic at -20°C showed 3.23% viability reduction, while probiotics at 25°C and 40°C showed 64.52% and 100% viability reduction. Heat attenuated probiotic cell count showed similar trend in its intactness. Significant reduction in antibacterial efficacy was observed for live probiotic stored at 25°C (16.27 to 9.77 mm; p < 0.05) and 40°C (16.40 to 4.77 mm; p < 0.05), compared to baseline antibacterial strength. Heat attenuated L. rhamnosus showed similar trend.

Conclusions: In conclusion, the present study underscores the potential impact of storage condition on the overall stability and therapeutic efficacy of probiotics throughout shelf-life.