Isolation of lactic acid bacteria (LAB) from erzincan tulum cheese, determination by molecular methods and genetically determining of their exopolysacchari̇des (EPS) production potential

The potential use of lactic acid bacteria (LAB) involved in the production of traditional fermented products as starter cultures depends on the diversity of their biochemical activities that play role on taste, structure, flavor properties of these products and their ability to produce relevant metabolites. The in situ exopolisaccharide (EPS) production characteristics of LAB during the fermentation both results in substantial improvement in the physicochemical properties of the final product and also play roles in the interaction of these species with their environement that may result in functional outcomes. In this respect, the aim of this thesis was to isolate LAB species with EPS production characteristics that might be the starter culture for Ezincan Tulum cheese productino, to investigate the presence of homopolymeric and heteropolymeric eps genes in these species and to characterize the EPS produced by these species. In this thesis, tulum cheese samples were collected from Erzincan and its villages and LAB species were isolated and identified from these cheeses. Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus brevis, Weissella paramesenteroides, Lactococcus garvieae and Lactobacillus crustorum strains were isolated from cheeses samples and PCR detection of eps genes in these species revealed the presence of both homopolymeric gand heteropolymeric eps genes in these species. The EPS production tests revealed that these species produced similar levels of EPS. It was observed that EPS prodcution levels of the selected straines altered in different media conditions. In order to reveal the sugar groups produced by tulum cheese isolates, these species were grown in pasteurized milk and MRS broth containinsg 3% lactose and EPSs were isolated. HPLC analysis of the EPSs revealed that all strains produced EPS that included only glucose. These results demonstrate the importance of EPS production in LAB species that have a significant impact on Erzincan Tulum cheese production.