FIG. 2.

Expression of pahA gene. (A) Expression of pahA was detected by Northern blot using total RNA isolated from P. chrysogenum E1 at 48, 72, 96, and 120 h of fermentation in standard penicillin G production conditions with and without PA. In the standard medium (with PA), expression is correlated with the penicillin production kinetics. The 5S rRNA signal was used as a loading control. (B) Northern hybridization of pahA with different P. chrysogenum strains grown in penicillin G production conditions. Duplicate lanes were loaded with total RNA from each of the following strains: lane 1, Wisconsin 54–1255; lanes 2 to 5, industrial strains with increasing penicillin productivity from left to right; lane 6, strain E1. The size of the pahA transcript corresponds to 1.6 kb.