Assessment of the viability of cultures of lactic acid microorganisms during their freezing and low-temperature storage

Relevance. A significant increase in microbiome-associated diseases, closely related to violations of the bacterial diversity and functions of the normal intestinal microbiota, dictates the need to develop and implement measures for the long-term preservation of individual representatives of the normal microbiota in order to create new strategies for modifying the composition of microbiomes. Methods. The influence of the technology of deep freezing and storage of intestinal isolates of lactic acid bacteria of 2 taxonomic groups isolated from poultry in the conditions of the Low-temperature automated storage of biological samples of the Departmental Collection of useful microorganisms for Agricultural purposes of the Russian Agricultural Academy (VKSM) on the MRS culture medium using 10 and 20% glycerin or 10 and 20% sucrose as cryopreservants was studied. The suspensions of the isolates were frozen at - 150 °C for 18 hours and then placed in an automated cryopreservation at -80 °C. Control of samples for safety Results. The technology of cryofreezing of lactic acid bacteria on MRS-broth using 10 and 20% glycerin or 10 and 20% sucrose as cryopreservants allows preserving the viability, physiological and  biochemical properties of intestinal isolates of lactic acid bacteria when stored for 18 months. All the protective media used (MRS-broth with glycerin 10 and 20%, MRS -broth with sucrose 10 and 20%) showed comparable results in the preservation of viability and acid-forming activity of Lactobacillus fermentum-2, Pediococcus pentosaceus 6p-3, Pediococcus pentosaceus 28p-1 isolates. Then the storage of Pediococcus pentosaceus isolate (28p-1) in a given parameter on a protective medium with 10 and 20% sucrose led to a decrease in the activity of acid formation.