Due to its climatic and geographical diversity as well as long history of production of traditional dairy products, SE Europe is a rich source of indigenous microbiota. The aim of our thesis was to isolate and identify as many as possible diverse lactic acid bacteria (LAB) from traditional dairy products of Slovenian, Serbian and Russian local dairy product producers, made from raw or heat-treated milk and with or without the addition of starter cultures (SC). Therefore, we obtained 37 samples of dairy products and 2 samples of raw milk, from different species of animals. From samples, made from either heat-treated or raw milk and mostly fermented with natural microbiota, 706 colonies were randomly isolated, purified and identified to the species level by the MALDI-TOF MS method. A significant proportion of identified microbiota was represented by the genus Lactobacillus, with predominant species of Lb. paracasei, Lb. plantarum and Lb. kefiri, and by the genus Lactococcus represented with Lac. lactis species. Enterococci, especially Ec. faecalis and Ec. faecium were also important, but more typical for traditional cheeses, while Leuc. mesenteroides was more typical for fermented milks and kajmaks. In addition to the typical LAB, we also identified less typical non-LAB representatives. Because the native microbiota is generally considered to be more diverse at the strain level than SC, we investigated Lac. lactis and Lb. paracasei isolates with RAPD-PCR analysis, isolated from 16 different dairy products. We determined bigger strain similarity in products with added SC and from heat-treated milk. Microbiota diversity is also influenced by the type of dairy product, ripening time and geographical area of production.
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