Optimization of the storage method of Lactococcus lactis ssp. lactis strains to stabilize their probiotic potential

Abstract

The object of the study were strains of Lactococcus lactis ssp . lactis isolated from microbiota of fermented milk products brought from Buryatia (Russia), Lebanon, Iran, which have high probiotic potential. The purpose of this work was to optimize the storage method of L. lactis ssp . lactis strains to stabilize their probiotic potential. The various storage methods were used - in skim milk with frequent passages and lyophilization. The cultures were lyophilized on a ‘Krist” installation of the “Betta A “(Germany). Lyophilized strains were restored and their physiological and biochemical properties were studied both immediately after recovery and in a number of passages after storage, their physiological activity was evaluated by the rate of clot formation in skim milk and antimicrobial activity using the microbiological method with the test-cultures and standard antibiotic solutions (Nisaplin, Chloramphenicol, Nystatin). The highest survival rate was found during lyophilization with preliminary treatment. When cultures were restored, the survival rate in the first passage was over 70%, the strains had a high level of antimicrobial activity on both gram-positive and gram-negative bacteria and fungi, including pathogens. The results of the study showed that the most effective method of preserving bacteriocin-forming lactococci is lyophilization using a complex protective environment of the composition (g/l): sucrose-100, gelatin-10, monosodium glutamate-10, sodium citrate-5, which ensures long-term crop life. The introduction of lactococci into the intestinal microbiota leads to the replacement of pathogens and is useful for people with lactase deficiency. Strains enrich the dairy product with biologically active substances, which, in addition to the nutritional effects, have a beneficial effect on health. Lyophilization in combination with pre-treatment of cells contributes to the preservation of their probiotic potential.