Molecular characterization of yeast isolated from white cheese

In this study, a total of 48 yeast strains were used as material from a total of 30 white cheese samples, 15 closed and 15 open packages, in different brands and packages, which were offered for sale from various markets in Samsun and Terme district market between 2006-2007. Yeasts can develop easily in white cheese, this is because these microorganisms have high enzyme activities in a wide range of water activities, pH and temperature abilities as well as high. Yeasts that develop in white cheese cause various deteriorations by causing undesirable structure and sensory changes such as bitter taste, yeasty taste, off-flavor, gas formation, softening and unwanted porous structure formation. This situation causes a decrease in various quality and product losses in white cheese. In addition, the excess number of yeast is seen as an important indicator that the hygiene and sanitation rules are not followed in the enterprises. Isolation and identification of yeast strains that develop on the cheese surface and are potential spoilage factors will contribute to the prevention of problems experienced in the production and storage of these products. In the study, PCR-RFLP method based on genotype characters and DNA sequence identification method were used to identify yeast strains isolated from white cheese. It was found that no difference was observed between 48 yeast strains of PCR-RFLP method. Sample yeast DNA sequences were subjected to blast, similarity, NJ and ML phylogenetic analyzes to determine the degree of relatedness. At the end of these analyses, Yarrowia lipolytica yeast strain was found to be dominant among the yeast strains isolated from white cheese. Moreover, the distinction in phylogenetic trees clearly shows that yeast strains subjected to phylogenetic analysis were isolated from "Market" and "Bazaar" samples. Because, while it was found that Y. lipolytica isolated from market samples were mostly closely related to reference yeast strains of European origin and commercially produced, Y. lipolytica isolated from bazaar samples were mostly found to have close affinity with mixed region origin and wild reference yeast strains. These results have been supported in various literatures. As seen in the study and in the literature, the origins of Y. lipolytica yeast strains were found to be different in the white cheese samples offered for sale in the bazaar. As a result, it is thought that the white cheeses offered for sale in the market will pose a risk both in terms of hygiene and health compared to the white cheeses offered for sale in the bazaars.With this study, it is aimed to prevent product losses caused by yeasts in the white cheese sector, as well as to shed light on studies related to its use in food, fermentation and biotechnology.