Mechanism of Antifungal Effect of Lacticaseibacillus paracasei C5 Against Aspergillus flavus and Its Application in Biopreservation of Bread

As a widely distributed mold species, Aspergillus flavus shortens the shelf life of food. Its capacity to synthesize aflatoxins seriously threatens food safety and human health. Given the limitations of conventional control methods and the increasing consumer preference for natural additives, microbial biocontrol agents are essential for ensuring sustainable food safety. This study investigated the antifungal mechanism and preservative efficacy of Lacticaseibacillus paracasei C5. Germination inhibition of A. flavus spores and morphological disruption of its mycelia were effectively induced by the cell-free supernatant (CFS) of L. paracasei C5. The CFS acts by interfering with ergosterol synthesis and compromising cell membrane integrity. Furthermore, CFS treatment augmented reactive oxygen species (ROS) levels and precipitated lipid peroxidation, compromising DNA integrity and instigating mycelial apoptosis. Transcriptomic profiling demonstrated a notable enrichment of differentially expressed genes (DEGs) in pathways pertinent to cell wall and membrane integrity, ribosomal biogenesis, and the oxidative stress response, elucidating a multi-target inhibitory mechanism of L. paracasei C5 against A. flavus. Finally, L. paracasei C5 showed a significant capacity to prolong the shelf life of bread. These results demonstrated the significant potential of L. paracasei C5 for biopreservation applications.