Fig. 4

Effect of the presence of glucose 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 the presence of glucose. 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. Sugar consumption and FopA production of ATCC 20611 cultured in the fermentation medium with 0.5% glucose (B), 2% glucose (C), 2% sucrose (D), 2% sucrose plus 0.5% glucose (E), 2% sucrose plus 2% glucose (F) as the carbon source. Values and standard deviation (SD) of triplicates are presented in the figure. Asterisks indicate statistically significant differences (**p < 0.01) as assessed by Student’s t test. n. s., no significant differences