Identification of an antifungal lipopeptide from Bacillus amyloliquefaciens HAU3 inhibiting the growth of Fusarium graminearum using preparative chromatography and 2D-NMR.
UNLABELLED: The presence of fungal contamination and its mycotoxins in animal feed is pervasive, posing a significant threat to the well-being and performance of animals, as well as the safety of animal-derived food products. In this work, we screened a strain of Bacillus amyloliquefaciens (B. amyloliquefaciens) HAU3 that exhibits efficient antifungal activity against the growth of Fusarium graminearum (F. graminearum). The antifungal activity was detected in the supernatant, with 20% sterile supernatant demonstrating an impressive antifungal rate of 98.46% against F. graminearum. The antifungal activity of the strain was evaluated through spectrum analysis and silage trials, revealing its effective antifungal activity against multiple fungal species. Furthermore, the strain is capable of degrading ZEN and its derivatives. The targeted disruption of fungal mycelial membrane was observed using scanning electron microscopy and transmission electron microscopy. Additionally, staining with the reactive oxygen species (ROS)-sensitive fluorogenic dye DCFH-DA and propidium iodide (PI) revealed that the strain induces accumulation of ROS in fungal mycelia. The active compounds underwent further separation, purification, and detection. The prominent active peak was identified through mass spectrometry and magnetic resonance spectroscopy. The molecular structure of the active compounds was predicted to be lipopeptides composed of 8 amino acids known as fengycin. The whole genome sequencing and informatics analysis unveiled a total of 13 gene clusters responsible for the synthesis of secondary metabolites. The antifungal effects of B. amyloliquefaciens HAU3 are exerted through the synthesis of fengycin, which selectively targets and compromises the integrity of fungal mycelia membranes, thereby making it a potential biocontrol agent for mitigating mycotoxin contamination in feed. IMPORTANCE: Mycotoxin contamination in animal feed, predominantly driven by Fusarium graminearum, represents a persistent threat to livestock health and food chain integrity. Here, we report the isolation of a soil-derived Bacillus amyloliquefaciens HAU3, exhibiting potent and broad-spectrum antifungal activity alongside efficient biodegradation of zearalenone and its derivatives. Mechanistic dissection reveals that fengycin, the principal bioactive metabolite, compromises fungal membrane integrity and elicits intracellular oxidative stress, culminating in hyphal collapse. Genomic profiling uncovers a diverse repertoire of biosynthetic gene clusters underpinning secondary metabolite production. These findings establish strain HAU3 as a promising microbial chassis for the development of next-generation biocontrol strategies aimed at mitigating mycotoxin burden in agroecosystems.