Fungal spoilage remains a persistent challenge in dairy products, particularly in clean-label yogurt and cheese that require effective natural preservation strategies. In this study, Lactiplantibacillus plantarum Yilife-LP06 was identified as a promising biopreservative strain based on its strong antifungal activity against Debaryomyces hansenii and Penicillium expansum, broad-spectrum antimicrobial activity, and efficacy in cheese and yogurt model systems. In natural cheese, processed cheese, and yogurt, Yilife-LP06 and its fermentation concentrate significantly inhibited fungal growth without adversely affecting the measured fermentation parameters. Metabolomic profiling showed that organic acids represented 22.05% of the differential metabolites, with phenyllactic acid (PLA) and hydroxyphenyllactic acid (HO-PLA) significantly enriched in the fermentation concentrates (P < 0.01). Plackett-Burman screening and Box-Behnken response surface optimization identified sucrose and sodium acetate as the major factors governing PLA biosynthesis, while L-phenylalanine supplementation increased PLA production to a predicted maximum of 1,597 mg/L. RT-qPCR analysis further indicated that carbon source optimization enhanced shikimate pathway flux through upregulation of aroA1, aroD, aroE, and tyrA, whereas precursor feeding promoted terminal PLA conversion via hisC and ldh induction together with feedback repression of upstream biosynthetic genes. These findings support the optimization of LAB-derived antifungal metabolite production and the development of clean-label biopreservation strategies for dairy applications.
Yang et al. (Mon,) studied this question.