Isolation and Identification of food Probiotic Saccharomyces boulardii by using traditional methods, Vitek 2 system and molecular identification methods.

Abstract

This study was aimed to isolate and identify Saccharomyces boulardii from Mangosteen fruits (Garcinia mangostana L.) by traditional and molecular identification methods To get safe and healthy foods probiotics for use, The isolates and two commercial strains were subjected to cultural, morphological and biochemical tests, The colonies of the isolates were spherical, smooth, mucoidal, dull and white to cream colour on SD agar media .The shape of cells was globose to ovoid and sometimes with budding, in a single form or clustered like a beehive. The isolates and two commercial strains were unable to metabolized galactose and lactose , Results shows that all isolates were unable to utilize potassium nitrate and not grow in the presence of (0.01%) cyclohexamide. Also the isolates and two commercial strains were identified by the Vitek 2 identification system, as S. cerevisiae with probability 90-94%, Since there are no data in this device includes S. boulardii. Because the cultural, morphological and biochemical tests didn’t provide sufficient evidence to distinguish between S. boulardii and S. cerevisiae, the probiotics strains must be identified up to genus and strain levels by internationally accepted methods, So the SbR7 isolate which shown high probiotic advantages and two commercial strains were diagnosed molecularly by using specific primers targeting sequence for the region (ITS) of the 5.8S rRNA gene Genomic DNA was isolated from SbR7 Isolate and ITS region of the 5.8S rRNA gene was amplified using PCR. PCR products was sequenced and compared with the sequence of this region in the DNA of S. boulardii available in GenBank (NCBI) using the program BLASTn. Results revealed, this isolate was almost genetically identical (99%) with S. boulardii standard strains.