Fig. 2

Inactivation of competing pathway genes and overexpression of the resistance genes a Schematic representation of the disruption of the target gene dnrU in S. peucetius. b The parental strain SIPI-7-14 and the engineered strain △U1 were verified by PCR. M: marker, 1: control (SIPI-7-14), 2: the engineered strain △U1 (351 bp in the knockout gene dnrU in the genome of strain SIPI-7-14). c Comparison of doxorubicin production and biomass by the SIPI-7-14 strain and the engineered strains △U1, △H4 and △X1 in shake flasks after 6 days of fermentation. The error bars indicate the standard deviations. d The parental strain SIPI-7-14 and the engineered strain △H4 were verified by PCR. M: marker, 1: control (SIPI-7-14), 2: the engineered strain △H4 (783 bp in the knockout gene dnrH in the genome of strain SIPI-7-14). e The parental strain SIPI-7-14 and the engineered strain △X1 were verified by PCR. M: marker, 1: control (SIPI-7-14), 2: the engineered strain △X1 (1221 bp in the knockout gene dnrX in the genome of strain SIPI-7-14). f The engineered strains △U1/drrC, △U1/drrAB, △U1/drrABC and △U1/drrD were generated by overexpressing the resistance genes drrC, drrAB, drrABC and drrD in the parental strain △U1, respectively, and were subsequently verified by fermentation in shake flasks to determine their doxorubicin production and biomass. Three parallel shakers were performed for each strain. g The transcription levels of the drrC gene were compared between △U1/drrC and △U1 by using shake flask fermentation broth collected on the 4th and 6th days. The error bars indicate the standard deviations