Exploring the antifungal mechanism of β-1,3-glucanase for effectively inhibiting the food contamination by Aspergillus flavus and Aspergillus fumigatus

Eco-friendly strategies are needed to solve the global public health problem of food fungal contamination. In this study, the mutant N54W of β-1,3-glucanase BglS27 with a 3.6-fold higher specific activity was constructed according to the structure comparison analysis. Molecular dynamics simulation revealed that Trp54 promoted and stabilized substrate binding, and facilitated the nucleophilic attack of catalytic residues. The mutant N54W exhibited higher antifungal activity against Aspergillus flavus and Aspergillus fumigatus. The assay of cell membrane integrity and mycelium hydrolysis elucidated that the enzyme hydrolyzes the structural β-1,3-glucans of the fungal cell to glucose and oligosaccharides, leading to cell rupture and death. Furthermore, the mutant N54W decreased the contamination rate of A. flavus and A. fumigatus in maize by 86.1% and 88.9%, respectively. Further optimization of the stability and efficiency of this enzyme in the actual food industry environment will contribute to its industrial application. These results provide meaningful information on the antifungal property of the mutant N54W at the molecular level and a promising efficient green antifungal preservative in the food industry.