Open AccessPhysiological response of S accharomyces cerevisiae to weak acids present in lignocellulosic hydrolysate
Author(s) -
Guo Zhongpeng,
Olsson Lisbeth
Publication year - 2014
Publication title -
fems yeast research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 92
eISSN - 1567-1364
pISSN - 1567-1356
DOI - 10.1111/1567-1364.12221
Subject(s) - trehalose , hydrolysate , yeast , biology , biochemistry , fermentation , vanillic acid , levulinic acid , saccharomyces cerevisiae , food science , glutathione , acetic acid , glycolysis , metabolism , hydrolysis , enzyme , catalysis
Weak acids are present in lignocellulosic hydrolysate as potential inhibitors that can hamper the use of this renewable resource for fuel and chemical production. To study the effects of weak acids on yeast growth, physiological investigations were carried out in batch cultures using glucose as carbon source in the presence of acetic, formic, levulinic, and vanillic acid at three different concentrations at pH 5.0. The results showed that acids at moderate concentrations can stimulate the glycolytic flux, while higher levels of acid slow down the glycolytic flux for both aerobically and anaerobically grown yeast cells. In particular, the flux distribution between respiratory and fermentative growth was adjusted to achieve an optimal ATP generation to allow a maintained energy level as high as it is in nonstressed cells grown exponentially on glucose under aerobic conditions. In addition, yeast cells exposed to acids suffered from severe reactive oxygen species stress and depletion of reduced glutathione commensurate with exhaustion of the total glutathione pool. Furthermore, a higher cellular trehalose content was observed as compared to control cultivations, and this trehalose probably acts to enhance a number of stress tolerances of the yeast.