Browsing by Subject "Saccharomyces boulardii"

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  • Ran, Li; Wan, Xing; Takala, Timo; Saris, Per (2021)
    The yeastSaccharomyces boulardiiis well known for its probiotic effects such as treating or preventing gastrointestinal diseases. Due to its ability to survive in stomach and intestine,S. boulardiicould be applied as a vehicle for producing and delivering bioactive substances of interest to human gut. In this study, we cloned the genelecCencoding the antilisterial peptide leucocin C from lactic acid bacteriumLeuconostoc carnosuminS. boulardii. The constructedS. boulardiistrain secreted a peptide, which had molecular weight corresponding to leucocin C in SDS-PAGE. The peptide band inhibitedListeria monocytogenesin gel overlay assay. Likewise, concentratedS. boulardiiculture supernatant inhibited the growth ofL. monocytogenes. The growth profile and acid tolerance of the leucocin C secretingS. boulardiiwere similar as those of the strain carrying the empty vector. We further demonstrated that the cells of the leucocin C producingS. boulardiiefficiently killedL. monocytogenes, also without antibiotic selection pressure. These results showed that antilisterial activity could be added to the arsenal of probiotic activities ofS. boulardii, demonstrating its potential as a carrier for therapeutics delivery.
  • Liljeroos, Anna (Helsingin yliopisto, 2020)
    Beer is the world´s most popular alcohol drink, with a long history. It is commonly made with baker’s yeast Saccharomyces cerevisiae. Yeast used for fermentation has an effect on the sensory properties of the product. Saccharomyces boulardii is a probiotic yeast. The objective of the thesis was to explore the use of probiotic yeast S. boulardii in wheat beer and develop it further with the help of sensory evaluations. S. boulardii is used to prevent travelers' diarrhea and as a help to many intestinal disorders. The use of probiotic yeast could make a new interesting product with functional properties. In the experimental part of the study beer was produced with two yeasts, S. cerevisieae and S. boulardii. The beer was matured in two different temperatures (20°C and 37°C). The four samples were compared to commercial reference product. One sample (C37) did not meet quality standards so it was left from sensory analysis. The sensory analysis was performed with 9 trained panelists by using generic descriptive analysis. Concentration for alcohol was measured with High Performance Liquid Chromatography (HPLC). Also pH value and the colour shade was measured. The samples were plated on agar plates to calculate colonies forming units (CFU) to test the yeast surviving in 1, 2 and 3 months time. Eight attributes were rated using visual analogue scales, anchored verbally at the end points. Sensory evaluation showed that the beer differed statistically significantly from each other in three attributes: appearance of foam, the mouthfeel of carbon dioxide and stale, musty smell. B37 was categorized in the same group in Tukey’s test with commercial product although the alc. vol.% was lower. The samples that were fermented in the room temperature had a musty smell and they had darker colour. pH values had only minor differences and the sourness did not have statistically significant differences in sensory analysis. Yeasty taste did not vary significantly between samples. B37 maintained colonies forming units better in the first month and B20 in the second and third measurement. B37 was the most similar to the commercial product, so further studies are encouraged to assess right fermentation conditions. The survival of the probiotic yeast was good, so the product has potential to the beer market.