Microbiological Studies on Cheese (II)

Determination of Yeasts found in Cheese Imported from Europe and North America

Abstract

Two hundred and fifteen isolates of yeasts obtained from 21 samples of cheese imported from Europe and North America were studied taxonomically and were identified with 15 species belonging to 9 different genera. More than a half of the isolates (134) were Debaryomyces hansenii, and followed by Candida lipolytica (27), Candida zeylanoides (14), Torulopsis candida (13), Cryptococcus albidus (11), Kluyveromyces lactis (3), Torulopsis sphaerica (3), Cryptococcus luteolus (2), Rhodotorula rubra (2), Saccharomyces italicus (1), Sporobolomyces roseus (1), Candida intermedia (1), Candida kefyr (1), Rhodotorula minuta (1), and Trichosporon cutaneum (1).
One hundred and thirty-four isolates of D. hansenii were divided into 4 subgroups by assimilation of lactose, formation of a pellicle, and colonial characteristics. More than a half of the isolates (61%) belonged to D. hansenii-type (assimilates lactose, and forms a pellicle and rough colony), and followed by D. subglobosus-type (34%, assimilates lactose, and not forms a pellicle, and smooth colony), D. nicotianae-type (3%, not assimilates lactose, and forms a pellicle, and smooth colony), and D. kloeckeri-type (2%, not assimilates lactose, and not forms a pellicle, and rough colony). The subgrouping has little taxonomic value since several isolates showed intermediate characteristics but has a value from an ecological point of view.
Isolates belonging to Cr. albidus showed characteristics resembled those of Cr. albidus var, albidus and Cr. albidus var. diffluens but could not be clearly separated into these two varieties because some isolates showed intermediate properties between the varieties. These two varieties should be combined.