Fig. 3

Effect of different promoters and fermentation media on the production of CM and NCM. (A) Analysis of CM and NCM production when cxnR overexpressed in wild-type strain and fermented on ISP2 plate. WT: CM-producing strain A. tsinanensis CPCC 200056; WT/e-CxnR: cxnR overexpression in 200056. The yield of CM in the two strains was compared with each other (Student’s t test, ^*p < 0.05). (B) Effect of different promoters driving the expression of cxnR on CM production in A. tsinanensis CPCC 200056. Different promoters represented different strains. ermE^*p: 200056/e-CxnR; kasO^*p: 200056/k-CxnR; sco5768p: 200056/5768-CxnR; gapdhp: 200056/g-CxnR; rpsLp: 200056/r-CxnR; isa2027p: 200056/2027-CxnR. (C) NCM production in S. coelicolor M1452/pL-CxnB-F cultivated in different fermentation media. The yield of NCM in each medium was compared with that in M1 medium (Student’s t test, ^**p < 0.01, ^***p < 0.001). (D) Production of CM and its congeners in 200056/2027-CxnR cultivated in different fermentation media. The yields of CM and NCM in each medium were compared with those in M1 medium (Welch’s t test, ^*p < 0.05, ^**p < 0.01). Values are presented as mean ± SEM (three independent conjugants for each strain)