Genetic Improvement of Saccharomyces boulardii R7 and Generate Suitable Strains for Synthesis and Expression of Recombinant Products

Saccharomyces boulardii R7 was mutagenized using UV radiation. Uracil auxotroph mutants were isolated and four of these mutants showed stable mutation. Two mutants SbR7M7 and SbR7M10 were chose for transformation according to their similar behavior with wild type (SbR7) isolate. The two mutants (SbR7M7 and SbR7M10) were transformed with pYES2, which was extracted from Escherichia coli Top10, and two transformants (SbR7T7, SbR7T10) obtained. The transformation was confirmed by isolating the plasmid (pYES2) from these transformants and used to transform E. coli Top10 (free of plasmid). Some probiotic properties were studied for the two transformants (SbR7T7, SbR7T10) compared with SbR7. They showed a noticed improvement in autoaggregation ability, an improvement of antagonistic activity toward E. coli: O157:H7 and Candida albicans and they reduced cholesterol ratio after 24 hr of incubation, however, the ratio increased after 48 hr of incubation.