Probiotic potential of Saccharomyces strains isolated from Litchi chinensis (Lychee fruit)

Recently, probiotic yeasts have become an interesting topic of research all over the world. Saccharomyces cerevisiae is well proven probiotic yeast against several gastrointestinal diseases. Current study aimed to explore the probiotic potential and antibacterial properties of Saccharomyces strains isolated from fresh lychee fruits available in local markets of Karachi, Pakistan. Probiotic potential and antibacterial activity of locally isolated probiotic yeast strains (named as S. cerevisiae BEL 1 and S. cerevisiae BEL 9) was studied against gastrointestinal pathogens using standard in vitro screening methods. Comparative analysis was also carried out with commercially available S. boulardii probiotic preparations. Furthermore, for probiotic potential, all the studied yeast strains were exposed to various stress conditions inherent of gastrointestinal tract i.e., thermo tolerance, pH tolerance, bile salts survivability and osmo-tolerance. Isolated strains (BEL 1 and BEL 9) were able to tolerate at the temperatures (40oC and 45oC), moreover survived in the presence of gastric juices, extreme bile salt concentrations (range 0.5%-2%) and different osmotic stress conditions (1M and 1.5 M NaCl). Optimal growth was observed at 37oC. Similar growth pattern and viability of BEL 1 and 9 was found for most of the stress conditions, when compared with the commercially available strains of S. boulardii. Therefore, isolated yeast strains BEL 1 and 9 will be considered as a potential bio-therapeutic agent because of the promising probiotic potential.