Optimization of the composition of the protein-carbohydrate base of the nutrient medium for the production of monospecific bacterial starter culture of Lactobacillus casei

Abstract

Mesophilic bacteria of Lactobacillus casei are used in the food industry not only to accelerate the cheese ripening, but also as a probiotic culture in functional foods. This article describes the results of studies to optimize the composition of the nutrient medium for the cultivation of mesophilic lactobacilli of Lbc. casei. The use of cheese whey as the basis of a nutrient medium to ensure the required level of energy metabolism leads to a decrease in production costs. However, cheese whey contains an insufficient amount of protein components and growth factors for the development of Lbc. casei. To solve the problem of providing mesophilic lactobacilli with adequate nutrition, cheese whey was enriched with an enzymatic milk protein hydrolyzates and yeast autolysate as a source of biologically active substances that stimulate the growth of lactobacilli. The optimized composition of the protein-carbohydrate base of the nutrient medium makes it possible to increase the biomass yield during deep liquid-phase cultivation and the initial infection dose of 1 % for 24 hours of cultivation to obtain the number of viable cells of Lbc. casei at the level of (8.5±0.2)⋅108 CFU/cm3, and as a consequence, to increase the efficiency of production of monospecific bacterial starter cultures.