YEASTS ISOLATED FROM LOCAL HONEY SAMPLES OBTAINED FROM THE STATE OF MATO GROSSO DO SUL 

Ifeloju Dayo-owoyemi (UNESP); Andre Rodrigues (UNESP); Osmar Malaspina (UNESP); Vladson Carbonari (UNESP); Fernando Carlos Pagnocca (UNESP)

In the course of a study to identify yeasts present in local honey samples obtained from Apis mellifera of the state of Mato Grosso do Sul, 13 yeast strains were isolated from 13 honey samples screened. Overall, grouping based on morphological and physiological characteristics as well as microsatellite (MSP-PCR) fingerprints yielded 8 distinct groups represented by strains MP2-2CA (n= 1 isolate), MP2-2CB (n= 1), MP7-7B (n= 1), MP8-8B (n= 2), MP9-9A (n= 4), MP12-12A (n= 2), MP14-14A (n= 1) and MP14-14B (n= 1). Various cell shapes ranging from oval, ellipsoidal, spherical and cylindrical were observed on the yeast isolates. Strains represented by MP12-12A and MP8-8B assimilated galactose and formed ascospores after 3 days of incubation in glucose yeast peptone broth. Strain MP2-2CA showed a similar fingerprint profile with yeasts in groups MP7-7B and MP9-9A, but differed by assimilating maltose and xilitol. Strain MP2-2CB assimilated galactose, maltose, lactose, D-xilose, D-arabinose and L-arabinose. Based on sequences of D1/D2 domains of the rDNA gene 11 isolates were identified as Zygosaccharomyces mellis (groups represented by MP2-2CA, MP7-7B, MP8-8B, MP9-9A, MP12-12A and MP14-14A) with nucleotide identities ranging from 97-100% according to NCBI-BLASTn. One strain (MP2-2CB) showed 100% sequence identity with Pseudozyma hubeiensis and strain MP14-14B was identified as Zygosaccharomyces sp. Physicochemical analysis of the honey samples showed that their concentration of reducing sugars ranged between 65.10% - 70.22%, with sucrose, glucose and fructose concentrations ranging between 0.69% - 2.28%, 29.62% - 31.62% and 35.79% - 38.77%, respectively. The present work revealed that the honey samples investigated presented few yeast species recovered by culture techniques. It is likely that the high sugar concentrations permitted the growth of osmotolerant yeasts, like Z. mellis. All strains recovered grew on 40% glucose medium but weakly in medium containing 0.5% glucose suggesting that these strains are likely adapted to high sugar concentrations.