Metabolic engineering of Bacillus subtilis 168 for the utilization of arabinose to synthesize the antifungal lipopeptide fengycin

Fengycin is a cyclic lipopeptide complex produced by Bacillus species. The focus of this study was to improve fengycin titer through promoter replacement and fatty acid pathway modification. Here, arabinose was used as a carbon source to study fengycin synthesis in B. subtilis 168. Firstly, the nitrogen source of the medium was investigated, and water-soluble soybean cake powder was identified as the optimal nitrogen source for fengycin synthesis, resulting in a titer of 121.20 mg/L. Secondly, the native promoter of the fengycin biosynthetic gene cluster was replaced with the phase-dependent promoter Pylb, which further increased fengycin titer to 137.05 mg/L. Thirdly, the synthesis of fengycin was further promoted through enhancing the supply of fatty acyl-CoA by deleting fadB as well as overexpressing yhfL, yngH and tesA. Fengycin titer of the resulting recombinant strain reached 258.41 mg/L. qRT-PCR revealed the underlying reason for the increase of fengycin synthesis. This study confirms the feasibility of using a phase-dependent promoter and fatty acid pathway modification to improve the titer of fengycin, providing a reference for the production of antifungal lipopeptide using arabinose.

Automated summary

This study successfully improved the titer of fengycin by replacing the promoter and modifying the fatty acid pathway. The phase-dependent promoter and enhanced supply of fatty acyl-CoA were effective in promoting fengycin synthesis. The findings provide valuable insights for the production of antifungal lipopeptide using arabinose.