Carbon Metabolism Modification in Bacillus subtilis for Improving Fengycin Production and Investigating Antifungal Activity of Its Homologous Components

Abstract

As a lipopeptide, fengycin exhibits environmentally friendly, safe, and long-lasting biocontrol efficacy. However, due to its complex structure and the challenges in chemical synthesis, it is primarily produced through biosynthesis. This study reports an improvement in fengycin production in Bacillus subtilis by engineering the central carbon metabolic pathway and blocking the carbon overflow pathway. The highest production achieved 1290.31 mg/L, representing a 2.05-fold increase compared to the original strain. Additionally, a coculture system was established in which Corynebacterium glutamicum supplied proline to strain CGF-PA, achieving a further increase in production to 2491.97 mg/L. The fengycin homologues were characterized using IMS-MS and separated by preparative liquid chromatography. The antifungal activities of fengycin homologues were quantitatively evaluated against Fusarium graminearum, Botrytis cinerea, Pyricularia oryzae, and Rhizoctonia solani, and their morphological changes were observed. The study also investigated the differences in antifungal activity among the fengycin variants. Components 4, 5, 6, and 7 exhibited relatively strong antifungal activity, and the various components of fengycin were found to work synergistically.

Keywords: antifungal activity; byproducts; carbon pathway modification; coculture; fengycin homologues.