Improving the viability of Lactobacillus plantarum VAL6 using environmental-stress adaptation

Abstract

To demonstrate the adaptation of lactic acid bacteria to environmental stresses can improve cell viability during freeze-drying, the Lactobacillus plantarum VAL6 strain was cultured under different stress conditions, including temperature, pH, and increase in CO₂ concentration. The results of densitometry analysis showed that the strain was able to survive in harsh environmental conditions such as at pH 2.5, the temperature at 47^oC, and in anaerobic conditions created by CO₂. In particular, the CO₂ intensification culture could stimulate an increase in the density of L. plantarum VAL6, reaching 9.4 compared to 9 LogCFU/ml under normal culture conditions. After cells were adapted to environmental stress at pH 3.5, the highest survival rate after freeze-drying of L. plantarum VAL6 was 28% (2,500 times higher than that of the control). The results showed the potential to use environmental stresses to increase the survival rate of starter lactic acid bacteria strains for food applications.