Fig. 6

Rational engineering of Streptomyces strains for high-level and selective isatropolone A production. (A) Quantification the production of isatropolone A (ISA A) and isatropolone C (ISA C) in the wild type strain (CPCC 204095) and its derivatives was performed using HPLC-MS analysis. The relative yields of ISA A and C in each strain were compared with those in the wild type strain (Student’s t test, *p < 0.05, **p < 0.01). Values are presented as mean ± SEM (three independent conjugants for each strain). (B) Schematic representation of the construction of SKO derivatives with different promoters driving the expression of isaF. The production level of ISA A in these derivatives was determined by HPLC-MS analysis. Values are presented as mean ± SEM (three independent conjugants for each strain). The yield of ISA A in each strain was compared with those in the SKO/eF strain (Student’s t test, *p < 0.05). (C) Heat maps showing the titers of isatropolone A in three SKO derivatives, each with different promoters driving the expression of isaF, across various combinations of different media and fermentation time points. “NA” indicates that ISA A was not detected. (D) The production curves of isatropolone A were obtained from three recombinant strains on M5 agar medium. Values are presented as mean ± SEM (two independent conjugants for each strain)