Fig. 1

Improvement of doxorubicin yield by resistance screening a Fifty milligrams/L doxorubicin was added to the seed medium for 2 days of culture, after which 10% of the inoculum was transferred to fresh seed medium 2 times. The seed culture mixture was diluted and spread onto a plate, and single colonies were selected for shake flask fermentation. The strain with the highest yield was selected for the next round of screening. b Doxorubicin-producing S. peucetius were screened under different conditions and verified by shake flask culture: (1) natural selection, (2) seed solution with 50 mg/L doxorubicin, (3) seed solution with 100 mg/L doxorubicin, and (4) seed solution with 150 mg/L doxorubicin. The error bars are the standard deviations of three replicates