Fig. 6

SEM of S. cerevisiae after treatment of phenolic acids. a The parental strain cells, b the control group of adapted strain, which obtained from sequentially transferring and culturing yeast parental strain cells in synthetic medium without phenolic acid at the same condition with Method I; c–e were adapted strains from Method E, I and K, respectively. All above strain cells were inoculated in the medium with phenolic acids mixture at concentration of IC75 at 30 °C with agitation at 150 rpm for 9 h. Circle marks the folds on the cell surface; Arrow marks the invagination of cell. f Percentage of cells with fold and invagination. Each sample was observed in three different area (35–90 cells), the percentage of cells with fold and invagination was calculated by the mount of cells with fold and invagination divided total cells in the observed area