6-Deoxyerythronolide B production through chromosomal localization of the deoxyerythronolide B synthase genes in E. coli

Chromosomal engineering was used to localize the deoxyerythronolide B synthase (DEBS) genes and propionyl-CoA carboxylase (PCC) genes to the BAP1 Escherichia coli chromosome creating the new strain YW9. YW9 then featured a plasmid-free heterologous pathway for the production of the polyketide product 6-deoxyerythronolide B (6dEB, a precursor to the antibiotic erythromycin) highlighted by the successful chromosomal integration of five genes total and three DEBS genes each approximately 10 kb in length. The new strain was tested for small-scale 6dEB biosynthesis and compared to 6dEB production from plasmid-derived gene expression at 22, 30, and 37 °C. YW9 produced 6dEB at each temperature tested; whereas, the current plasmid-based system could only produce 6dEB at 22 and 30 °C. As determined by MS analysis, average production levels for YW9 were 0.47 (22 °C), 0.52 (30 °C), and 0.11 (37 °C) mg/L.