Improving the Yield of Xenocoumacin 1 by PBAD Promoter Replacement in Xenorhabdus nematophila CB6

Xenocoumacin 1 (Xcn1), which is produced by Xenorhabdus nematophila CB6, exhibits strong inhibition activity against plant pathogens, especially fungi and oomycetes. Therefore, it has attracted interest in developing into a novel biofungicide applicable for protection. However, its low yield with concomitant high cost during the fermentation process limits widespread application. In this study, we replaced native promoter of xcnA arabinose-inducible araBAD (PBAD), well-known widely used expressing heterologous genes, to evaluate effects on Xcn1 antimicrobial activity. Compared wildtype strain, was improved from 68.5 mg/L 249.7 (3.6-fold) 234.9 (3.4-fold) at 0.5% 1.0% L-arabinose concentration, respectively. We further explored transcription level biosynthesis related genes found that their upregulation resulted improvement Xcn1. Moreover, Bacillus subtilis Phytophthora capsici determined agar diffusion plate growth assay, as expected, also be enhanced. The promoter-replacement strategy utilized here improves efficiently, provides basis industrial production