Effect of salt and sugar osmotic stress on the viability and morphology of Saccharomyces boulardii

DOI: 10.22161/ijeab/1.3.43

Abstract:
Changes in the viability, composition and morphology of the probiotic yeast Saccharomyces boulardiiwerefollowed inhyperosmoticYPD broths withNaCland sucrosein concentration ranges from0.2 to 2M. Samples were observedbyscanning (SEM) and transmission (TEM) electron microscopy. SEM revealed changes inthe morphology (swelling) in the walls ofthe yeasts grown in high-osmolarity broths. TEM showed that, as a result of the high osmolarity, the cell wall was thickenedand vesicles were formed in the cytoplasm. The growth kinetics results indicated thatS. boulardiicould be considered as anosmotolerantyeast, since it could still grow and reach concentrations of3.4x105 and 3.6x107 CFU/mL at sucrose concentrations of 2.0 M and 1.5Mrespectively. The results also suggested thatthis yeast could also be consideredhaloduric sincecell concentrationsof3.9x106 and 3.4x105CFU/mLcould be maintained in broths with 0.4 and 1.4MNaCl respectively. S. boulardii was still able to produce 0.5% ethanol in the 2.0 M broth.

Keywords:
osmotic stress, Saccharomyces boulardii, viability, trehalose, glycerol.

Cite this Article: