Fig. 2

Screening and identification of novel regulatory genes required for the production of raw starch-degrading enzymes (RSDEs) in Penicillium oxalicum. a RSDE activities in strains with deletion of candidate regulatory genes and grown in medium containing soluble corn starch as the sole carbon source for 4–6 days after direct inoculation. The parental strain ∆PoxKu70 was used a control. Asterisks indicate significant differences (**P < 0.01; *P < 0.05) between the deletion mutants and the parental strain ∆PoxKu70 according to Student’s t test. b, c RSDE activities in the deletion mutants ∆POX01907 and ∆PoxKu70 and the complementary strain CPOX01907. P. oxalicum strains were cultivated in medium containing soluble corn starch for 2–4 days after transfer from glucose. Asterisks indicate significant differences (**P < 0.01) between ∆POX01907 and ∆PoxKu70 or CPOX01907, as assessed by Student’s t test