Isolation, Characterization, and Identification of Yeasts Associated with Foods from Assiut City, Egypt

The objective of this work was to isolate, characterize physiologically, and identify yeasts associated with foods from Assiut city, Egypt. Fifty-two colonies of yeasts associated with orange, mandarin, tomato, squash, sobia drink, mango juice, sugarcane juice, yogurt and buttermilk samples, collected from Assiut City, Egypt, were isolated. Out of which, Eleven isolates were selected randomly and subjected to morphological, biochemical studies and molecular identification techniques employing sequence of internal transcribed spacer (ITS) regions and partial D1/D2 large-subunit domains of the 26S ribosomal RNA. Identified yeasts were belonged to six genera and species; four species belonged to ascomycetes: Debaryomyces hansenii (five isolates), Saccharomyces cerevisiae (one isolate), Candida tropicalis (one isolate), and Pichia kudriavzevii (one isolate). In addition, two yeasts species belonged to basidiomyces: Rhodotorula mucilaginosa (two isolates), and Trichosporon dulcitum (one isolate). In spite of low frequency of yeasts isolates on the tested food, mango juice and buttermilk showed the higher sources for incidences during this study.