Influence of Global Regulatory Factors on Fengycin Synthesis by Bacillus amyloliquefaciens TF28

Fengycin, a lipopeptide synthesized by Bacillus species, exhibits pronounced antifungal activity; however, its low production titer remains a primary constraint to broader application. Global regulatory factors constitute key actionable targets for enhancing microbial synthesis. Here, we verified the ability of Bacillus amyloliquefaciens TF28 to produce fengycin with potent inhibitory activity. Transcriptomic analysis identified five global regulators linked to fengycin biosynthesis in this strain. Following their overexpression, fermentation kinetics indicated that while these regulators generally did not affect glucose utilization, each exerted a distinct effect on cell growth and fengycin production. Specifically, degQ overexpression increased fengycin production to 116.0 mg/L, corresponding to a 23.40% increase relative to the strain without degQ overexpression, whereas overexpression of degU, sigmaH, phoP, and abrB reduced it. Moreover, degQ and abrB overexpression modulated the expression of key fengycin synthetase genes, including fenA and fenB. Collectively, these findings establish that degQ, degU, sigmaH, phoP, and abrB functionally regulate fengycin biosynthesis in B. amyloliquefaciens TF28, providing a conceptual framework for the rational design of engineered strains with enhanced fengycin productivity.