Sorbitol-Mediated Shift of C₁₄/C₁₅ Iturin W Homologue Ratio in Bacillus sp. wsm-1

The reliance on conventional antibiotics and fungicides in food and agricultural systems drives drug-resistant pathogen spread and environmental contamination. Lipopeptides represent an eco-friendly alternative, but their efficacy is often limited by the presence of homologues with varying activities. Previously, we identified a novel lipopeptide, iturin W, whose C₁₄ variant exhibits superior efficacy against foodborne pathogens, whereas the C₁₅ homologue shows greater potency against plant pathogens. Notably, sorbitol supplementation shifts the homologue ratio from C₁₅ towards C₁₄ in iturin W. Here, we integrated transcriptomics, gene knockout and fermentation analyses to uncover the underlying mechanism. Our findings demonstrate that sorbitol induces metabolic reprogramming by enhancing glycolysis and oxidative phosphorylation while suppressing arginine and histidine biosynthesis. Key factors influencing this metabolic flux include SplA, DeoR/GlpR, RpoN and ResE. Importantly, knockout of splA significantly boosts the yield of C₁₄ iturin W. Furthermore, high aeration combined with histidine/arginine shifts production towards the C₁₅ variant, while low aeration with sorbitol enriches the C₁₄ form. Collectively, this work provides a mechanistic basis for rationally engineering microbial strains to optimize lipopeptide profiles, enabling precise biocontrol of bacterial versus fungal pathogens, thereby reducing reliance on synthetic chemicals and mitigating antimicrobial resistance in food and agricultural systems.