Abstract
In the area of microbial production of valuable chemicals, plasmids have been widely applied for overexpressing rate-limiting enzymes with high yields. However, the effect of antibiotic concentrations on the transcription of target genes in E. coli is less involved in previous reports. In this study, we constructed E. coli strains expressing the reporter gene and the kanamycin resistant gene in an operon, and analyzed the transcription levels of the reporter gene and the fluorescent intensity of the recombinant E. coli under different kanamycin concentrations. We found that the growth and gene transcription of the recombinant strain were affected obviously by the concentration of kanamycin, indicating the importance of fine-tuning of antibiotic concentrations in microbial fermentation.