IN VITRO PRELIMINARY IDENTIFICATION OF PROBIOTIC PROPERTIES OF S. cerevisiae STRAINS

Objective. To evaluate probiotic properties of two native strains of S. cerevisiae. Materials and methods. Strains were used in assays for tolerance to biliary salts, pH, temperature and adhesion to Salmonella spp., E. coli and Shigella spp. and antagonism. A 33 x 3 factorial design was used, with three levels for each factor (strains, pH and initial concentration of substrate (S0 )) by triplicate, to establish the culture conditions for each strain. A commercial strain (B) was used as control. The selected strain was cultured in a 2L bioreactor; the biomass was dryed by temperature and the resulting product was assayed to determine N2 concentration and cellular viability. Results. Strain A (from sugar cane), tolerated pH 3 ± 0.2, 0.3% (w/v) of biliary salts and 42°C. The factorial ANOVA found significant differences between the 27 assays (p<0.05) and surface analysis found that the interaction between factors strain and S0 was significant, suggesting for the optimization process the use of strain A and increasing concentrations of S0 . Results were reproduced in bioreactor with mx 0.31h-1, dt 2.18h and Y(x/s) 0.126g/g. the dry biomass obtained was viable and yielded between 6.3 and 6.9% N2/g. Conclusions. Native strains were identified with probiotic properties such as pH, biliary salt and temperature tolerance, and adherence to Salmonella spp., E .coli and Shigella spp.