Occurrence and identification of yeast species isolated from Egyptian Karish cheese

Abstract

This study aims at identifying the diversity and abundance of yeast associated with Egyptian Karish cheese, employing comparison between conventional laboratory techniques and API20 kits techniques in yeast identification. A total of one hundred samples (fifty each) of Egyptian raw and pasteurized Karish cheese milk were randomly collected from farmers and markets in Cairo and Giza Districts. The occurrence of yeast in raw and pasteurized Karish cheese milk were 100 and 38% with a mean value of 7 ± 1.1 l and 1 ± 0.31 log10 cfu g−1, respectively. Yeast strains isolated from both raw and pasteurized karish cheese samples were identified and characterized using both conventional methods and API 20 C AUX as a commercial identification system. The most prevalent isolates belonged to Trichosporon cutaneum (25%),Candida catenulata (23%), Yarrowia lipolytica (13%), Debaryomyces hansenii (13%),Kluyveromyces lactis (6%), Geotrichum candidum (7%), Candida zeylanoides (5%), Candida lambica (3%), Candida albicans (2%), Cryptococcus formans (1%), Rhodotorula glabrata (1%) and Saccharomyces cerevisiae (1%). There was no significant difference (P≥ 0.05) between the conventional method and the API20 kits test. However, the results of this study reveal that API 20 kits are simple, highly useful and are commercially available kits that considerably shorten the time required for the identification of yeast in cheese. Key words: Yeast identification, Karish cheese, API 20 kits.