Genotypic Identification of Yeasts Isolated from Yaghnobi Fermented Milk

The Yaghnob Valley in Tajikistan is inhabited by a small isolated human population. The area is geographically isolated, causing the inhabitant’s culture, food and lifestyle to remain uninfluenced by the rest of the world. Traditional methods of fermenting milk involve the use of indigenous microorganisms, leading to the production of a variety of fermented milk products. The people in Yaghnobi produce a fermented milk from goat, which constitutes one of their main foods. The aim of the current work was to determine which yeasts were present in the original Yaghnobi fermented milk as well as in the same product reproduced at home for three years with monthly reculturing in cow milk. Thirty yeasts have been isolated using different lab media such as M17, MRS, WL,YPD and YPD plus chloramphenicol, and colonies were re-cultivated until pure. Twenty isolates have been obtained from the original product and 10 from fermented milk reproduced at home. They were identified by Sanger sequencing of the amplified ribosomal Internal Transcribed Spacers (ITS1-4). Furthermore, RFLP analyses of the ITS1-4 region were performed when quality, coverage or similarity of ITS1-4sequences did not permitted the unambiguously identification of the yeast isolates. Only for Saccharomyces cerevisiae, identity was also confirmed with GTG5Rep PCR. The results showed the presence of Kluyveromycesmarxianus (11), Pichia fermentans (7) and Saccharomyces cerevisiae (10) in both products. However, Kluyveromyceslactis (1) was found in the original fermented milk sample and Kazachstaniaunispora(1) in home maintained fermented milk. Great attention has nowadays been devoted to microbial resources and the study of traditional fermented products can be a very interesting source of microbial biodiversity. This study provides for the first time data on yeast composition and characteristics in naturally Yaghnobi fermented milk, showing an unexpected richness in yeast communities leading to fermented milk production.