Fig. 4

Expression of phytase from the HSP12 promoter and its functional mapping. (A) Three independent clones containing an integrated pHSP12-phytase construct were processed as in Fig. 2A, and phytase activity was determined in the medium supernatant at different times after induction. Data are the mean ± SEM from 2 or 3 independent cultures for each clone. (B) Constructs containing diverse versions of the HSP12 promoter fused to the phytase ORF were integrated into the genome. The inverted red triangle denotes the position of the 5’ end of the construct assayed in panel A (denoted as pHSP12 in the bar graph). Predicted transcription factor-binding sites (with a p value < 2 × 10^− 5) are mapped at the bottom of the cartoon. Phytase activity was determined after 72 h of induction for all strains, and the induced/non-induced ratio was calculated. Data are presented as the mean ± SEM from 8 independent cultures for H1 to H5 and 4 cultures for pHSP12. *, p < 0.05, ***, p < 0.001