Isolation and identification of yeast in yak milk dreg of Tibet in China

Abstract

Yak milk dreg is a popular dairy product with a unique flavor which is frequently consumed in Tibet. The aim of this study was to investigate the occurrence and distribution of yeasts in yak milk dreg of Tibet. Ninety-one yeast colonies were isolated from ten yak milk dreg samples, and the isolates belonged to seven genera and ten different species based on the phenotypic characterization and analysis of ITS/5.8S ribosomal DNA (rDNA) gene. The distribution of each species among ten samples was as follows: Kluyveromyces lactis (6/10), Pichia fermentans (6/10), Saccharomyces cerevisiae (6/10), Rhodotorula mucilaginosa (6/10), Kluyveromyces marxianus (5/10), Pichia kudriavzevii (4/10), Torulaspora delbrueckii (2/10), Torulaspora quercuum (2/10), Debaryomyces hansenii (1/10), and Cryptococcus albidus (1/10). The present study reports for the first time the yeast profile in yak milk dreg products of Tibet in China, which provides useful information and yeast strain resource for further studies involving probiotic strain selection and starter culture design for the industrial production of yak milk dreg.