Evaluation of potentially probiotic attributes of certain dairy yeast isolated from buffalo sweetened Karish cheese

Egyptian traditional cheese has a long history and still represent an important part of the Egyptian diet. A lot of scientific studies in probiotic topic is usually related to bacteria, in particular lactic acid bacteria, and there is lack of information about potentially probiotic yeasts, except Saccharomyces boulardii. In the current study, 50 samples of traditional Egyptian buffalo sweetened cheese randomly were collected from five local Egyptian markets for yeast isolation. Isolated yeast species were identified using API20 kits techniques and the most frequently isolates were genotypically confirmed identified using the variability in the ITS rDNA. Appropriate in vitro assays have been conducted to examine their probiotic potentiality counting acid and bile salts tolerance, stimulated gastrointestinal tract tolerance, cell adhesion/hydrophobic characteristics, killer toxin productivity and antimicrobial activity against some clinical and food borne pathogens. The incidence of the obtained yeast taxa was found to be; S. cerevisiae (25%), Wickerhamomyces anomalus (23%), Pichia kudriavzevii (19%), Kluyveromyces lactis (17%), Geotrichum candidum (6%), Debaryomyces hansenii (4%), Candida tropicalis (3%), Cryptococcus neoformans (1%), Rhodotorula glabrata (1%) and Trichosporon cutaneum (1%). The most frequently isolates (S. cerevisiae, W. anomalus and P. kudriavzevii) exhibited high tolerance to bile salts elevated concentrations up to 2.0 %. W. anomalus could withstand the elevated bile salts concentrations and it was the most tolerable yeast isolate to intestinal juice environment. W. anomalus showed the lowest eradication from intestinal mucosa as indicated by the hydrophobicity average percentage 11.891% to xylene comparing to the P. kudriavzevii which showed the highest hydrophobicity average percentage of 46.185% to chloroform. Yeast isolates S. cerevisiae, W. anomalus and P. kudriavzevii (particularly W. anomalus) were recognized as ideal potentially probiotic model having in vitro properties that make them favorable candidates for probiotic applications.