Effect of steroidal saponins from Agave on the polysaccharide cell wall composition of Saccharomyces cerevisiae and Kluyveromyces marxianus

In the fermentation process of distilled spirits from Agave sugars, saponins inhibit the growth of yeasts during this procedure. This type of compound is present in the must, and the mechanisms of the cell growth inhibition are poorly understood. The fundamental objective of this work was to study the effect of saponins on the cell walls of the fermentative yeasts Saccharomyces cerevisiae and Kluyveromyces marxianus. This study was performed in batch and continuous cultures, adding pulses of saponins extracted from the leaves of Agave durangensis and Agave salmiana ssp. crassispina. The saponin extract from A. durangensis exhibited a stronger growth inhibitory effect in both yeast strains than A. salmiana saponin extract due to the structure of the saponins. However, in K. marxianus growth recovery was observed, because these strain showed saponinase activity that performed the saponin hydrolysis. Finally, microscopic observations confirmed the changes in the wall cell of S. cerevisiae and K. marxianus. (C) 2016 Elsevier Ltd. All rights reserved.