Fig. 5

Adaptive processes on phenolic acids tolerance of S. cerevisiae during SSF of CCR. a Fermentation performance; b yeast cell growth. The colony-forming units (CFU) of the strains on petri dishes were counted for evaluation of cell growth viability. PS represents the parental strain cells; Control was the control group of adapted strain, which obtained from sequentially transferring and culturing parental strain cells in synthetic medium without phenolic acid with the same process as Method I; E, I and K were adapted strains from Method E, I and K, respectively. The prehydrolysis was performed at 50 °C and pH 4.8 for 12 h, then SSF was performed at 37 °C at pH 5.5. The cell growth was represented by the colony-forming units (CFU) of the strains on petri dishes