Isolation and identification of probiotic yeasts from various sources

There has been a significant increase in the use of probiotics in recent years. They are frequently used in modulating the nutritional properties of foods, regulation of bowel balance; moreover, they are used in the treatment and prevention of various diseases. Numerous studies aimed to reveal the effect of probiotics on different diseases. It has been determined that probiotics can be used in the prevention and treatment of liver diseases, vaginal infections, gastrointestinal diseases, allergic diseases and cancer. Additionally, probiotics has been used in the treatment of post-operative complications as well as in the maintenance and protection of oral and dental hygiene. Studies on microorganisms and their applications as probiotics are increasing rapidly. Such studies aim to discover more potent probiotic strains that can prevent or treat many diseases. In our study, 140 yeasts were isolated from 36 different sources. All of these isolates were subjected to various tests to investigate their probiotic and technological properties. The ability of isolates to survive in the gastrointestinal tract, resistance to bile salt, antagonistic effects against various pathogens, susceptibility to antibiotics, acetic and lactic acid resistance were among the tests proceeded to detect their probiotic properties. On the other hand, catalase, β- glycosidase, lipase, urease, protease, amylase enzyme activities, different salt ratios, different pH and temperature values were investigated to test their technological characteristics. 26S rDNA was amplified using PCR to identify the 48 yeast isolates which gave the best results in all of the probiotic and technological screening tests. The isolates were identified as follows: Kluyveromyces sp. (1 isolate), Kluyveromyces lactis (1 isolate), Kluyveromyces marxianus (1 isolate), Candida intermedia (1 isolate), Candida glabrata (1 isolate), Candida quercitrusa (1 isolate), Candida tropicalis (1 isolate), Wickerhamomyces sp. (1 isolate), Pichia sp. (1 isolate), Clavispora lusitaniae (2 isolates), Candida parapsilosis (2 isolates), Pichia fermentans (2 isolates), Debaryomyces hansenii (2 isolates), Saccharomyces sp. (2 isolates), Candida zeylanoides (3 isolates), Yarrowia sp. (3 isolates), Saccharomyces cerevisiae (1 isolate), Pichia kudriavzevii (3 isolates), Yarrowia lypolitica (1 isolate), Wickerhamomyces anomalus (18 isolates).