Fig. 3

Effect of different sucrose concentrations on fopA expression and β-fructofuranosidase (FopA) production in A. niger ATCC 20611. A RT-qPCR analysis of the changes of fopA expression levels in response to various sucrose concentrations. Actin was used as the reference gene and gpd was used as the control gene. The 2^−ΔΔCt method was used for calculating relative expression levels. B The changes of β-fructofuranosidase production levels in response to different sucrose concentrations. Values and standard deviation (SD) of triplicates are presented in the figure. Asterisks indicate statistically significant differences (*p < 0.05, **p < 0.01) as assessed by Student’s t test