Some properties of lactic acid bacteria isolated from natural sources

Cheeses are a group of fermented dairy products manufactured worldwide. The fermentation process is carried out by lactic acid bacteria, which may function as starter cultures or as an additional microflora affecting the ripening process of cheese. Cheese production is a complex process influenced by various factors, such as the sodium chloride content. This is an important indicator in the technical process for producing different types of cheese.

The aim of this research was to isolate lactic acid bacteria (LAB) from natural sources and home-made fermented milk products from the Belgorod Region, Russia, and to investigate their individual characteristics.

During the course of the research, ten strains of LAB were isolated. All of the isolated strains could grow in the presence of 5% NaCl. Some isolates could tolerate concentrations of NaCl as high as 6% or more. The ability of the LAB to produce lactic acid and aromas is a crucial factor in the production of the final product. For this reason, the titratable acidity (◦T) was determined for each strain, as well as the ability of certain strains to form gas-like compounds on a sodium citrate medium. Based on the evaluation of culture characteristics, morphological features, and biochemical properties and a 16S rRNA sequence analysis, the isolated bacteria were identified as representatives of Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris.

The isolated strains of LAB have great potential as starter cultures for the production of cheese. Further research could investigate the features of their enzymatic activity in order to create an optimal microbial composition for starter cultures.

The work was supported by grant №075-15-2024-174 (project no. 20180177).