Fig. 4
Synergistic action of alkaline-pretreatment and oxygen-radical treatment on lignin-derived phenolics generated from rice straw. a HPLC chromatogram of vanillin and p-coumaric acid in the alkaline-pretreated rice straw slurry with or without oxygen-radical treatment for 20 min. Peaks of vanillin and p-coumaric acid at retention times of 38.0 min and 39.8 min, respectively. Effects of oxygen-radical treatment of the alkaline-pretreated rice straw slurry on the b growth and c ethanol production of S. cerevisiae. Vanillin and/or p-coumaric acid were added to the oxygen-radical-treated suspensions at final concentrations of 3.3 mM and/or 2.1 mM, respectively, followed by determination of yeast growth and ethanol production. Error bars represent the mean ± standard error of the mean of three independent experiments