Cell ultrastructure and protein expression of hanseniaspora yeasts under the effect of ethanol stress

Summary

The aim of this study was to evaluate the responses of Hanseniaspora opuntiae (Ho 41) and H. guilliermondii (Hg 43) to ethanol stress, analyzing the ultrastructures and protein expression profiles under increasing ethanol concentrations. The ultrastructure was examined by scanning electron microscopy (SEM) and the protein expression from the electrophoretic profiles (SDS-PAGE). In the microscopic analyses, the strains cultivated in Yeast Malt Agar without ethanol showed young cells with apiculate morphology, bilateral budding and concave distal poles. At the start of stress, in the presence of 3% ethanol, the cells showed multiple scars in the form of rings, and with 6% ethanol they presented changes in cell wall integrity, plasmolysis and the activation of cell autolysis. In the electrophoretic analyses of both Ho 41 and Hg 43, an increase in the expression of a 100 kDa peptide was noted with increasing ethanol in the media, indicating that this was a heat shock protein (HSP). The HSPs have been patented as markers for organisms of biotechnological interest since the conditions necessary to obtain bioproducts often require cultivation under stress. Thus this protein could be indicated as a molecular marker for the bio-prospection or genetic enhancement of non-saccharomyces strains more resistant to the fermentation process used in winemaking.

Keywords:
Wine; Resistance markers; Cell ultrastructure