Quantification and Characterization of Mannan Oligosaccharide Producing Yeasts isolated from Various Food Products

In the present investigation, an attempt has been made to screen and identify the isolates of yeast rich in mannan oligosaccharide (MOS) from different food sources collected from local market of Mumbai, India. Out of the forty-eight varied yeast strains obtained using selective and growth media, eighteen isolates were shortlisted on the basis of their MOS yield. The MOS yield obtained from Wickerhamomyces anomalus strain isolated from home-made dahi was even higher (33%) than that obtained from the traditionally used Saccharomyces cerevisiae strain (590.52 ± 8.25 vs 442.85 ± 4.25 mg/L). The reasonably good yield was found in Pichia casonil from grape juice (354.70 ± 1.02 mg/L) and Candida glabrata strain from carrot juice (350.8 ± 2.52 mg/L); however, the lowest yield was of Debaryomyces hansenii SZ10 (73.5 mg/L) grown on yogurt. Identification of the isolates was undertaken using Biomérieux VITEK ® 2 system and molecular fingerprinting by polymerase chain reaction-random amplified polymorphism DNA (PCR-RAPD) using microsatellite M13 primer and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of amplified 18S intergenic transcribed spacer region of ribosomal DNA (rDNA) after subjecting it to digest with three restriction endonucleases i.e. Hae III, Msp I and Hinf I. Based on the better yield, it was concluded that W . anomalus can be exploited as an alternative of S . cerevisiae yeast stains for commercial mass scale MOS production for human food and animal feed industries in future.