Effect of Pediococcus pentosaceus DB12 Cell-Free Supernatant on Controlling Aspergillus flavus Contamination in Postharvest Fresh Peanuts

Fresh peanuts (Arachis hypogaea L.) are highly susceptible to Aspergillus flavus contamination, leading to rapid quality deterioration. Lactic acid bacteria (LAB) are well established as natural agents for preserving agricultural products and inhibiting pathogenic microorganisms. However, their efficacy against A. flavus in fresh peanuts remains underexplored. This study evaluated the efficacy of Pediococcus pentosaceus DB12 cell-free supernatant (P. pentosaceus DB12 CFS) in mitigating A. flavus contamination in fresh peanuts, integrating assessments of quality parameters, microbial indices and untargeted metabolomics. Results demonstrated that P. pentosaceus DB12 CFS effectively mitigated A. flavus-induced deterioration in fresh peanuts, as evidenced by improved retention of color, textural hardness, and weight during storage. P. pentosaceus DB12 CFS also significantly reduced total number of mold colonies and mildew rate. Furthermore, it suppressed electrolyte leakage and malondialdehyde accumulation, inhibited peroxide and acid value elevation, and minimized the degradation of soluble sugars and sucrose. Metabolomic analysis further revealed the activation of phenylalanine metabolism, stilbenoid, diarylheptanoid and gingerol biosynthesis, and glutathione metabolism, thereby enhancing disease resistance in fresh peanuts. This study not only establishes the efficacy of P. pentosaceus DB12 CFS in mitigating postharvest A. flavus contamination in fresh peanuts but also provides a foundation for developing safe and efficient biocontrol technologies.