072: Identification of Novel Bacillus Amyloliquefaciens A-1 and Its Surfactin-Based Application for Biocontrol of Fungal Contamination in Agricultural Products

Introduction

Fungal contamination and mycotoxins pose significant threats to food security and health, with chemical control methods facing limitations such as environmental impact and residues. Biological control, especially using Bacillus species like Bacillus amyloliquefaciens, offers eco-friendly alternatives due to their antimicrobial metabolites, such as surfactin. This study identifies strain A-1, demonstrating its antifungal potential against A. westerdijkiae and A. flavus, isolates surfactin as the active compound, and enhances its production through genetic and fermentation optimization, providing an effective biocontrol strategy for agricultural product safety.

Methods

This study screened and identified Bacillus amyloliquefaciens A-1 for antifungal activity and isolated surfactin using plate confrontation assays, SEM/TEM, transcriptome analysis, and HPLC-Q-TOF-MS. The antifungal activity of crude lipopeptides was tested against Aspergillus flavus and A. westerdijkiae. A-1 was applied to pears, maize, and peanuts to assess its ability to inhibit fungal growth and mycotoxin contamination. Spore counts were measured with a hemocytometer, and AFB1 was quantified using immunoaffinity column purification and HPLC-FLD methods.

Results

This study identified Bacillus amyloliquefaciens A-1 as a potent biocontrol agent against Aspergillus flavus, significantly inhibiting fungal growth and AFB1 production. A-1 disrupted fungal structures and key metabolic pathways, down-regulating AFB1 regulatory genes aflR and aflS. Genome analysis identified surfactin as the main active compound, with its production enhanced through fermentation optimization using alanine, threonine, and Fe²⁺. A-1 effectively reduced fungal decay in pears and mildew in maize and peanuts, demonstrating strong antifungal activity.

Significance

This study identifies Bacillus amyloliquefaciens A-1 as a potent, eco-friendly biocontrol agent against fungal spoilage, offering a sustainable alternative to chemical fungicides. It provides a foundation for improving agricultural sustainability, reducing food waste, and enhancing food safety through practical and environmentally responsible applications.

Authors: Yafan Hu, Fuguo Xing, Zipei Zhang, Ruojie Zhang