The concentration-dependent impact of quorum-sensing signal molecule 2-phenylethanol on the flavor metabolite profile of Lactiplantibacillus pentosus 1 in a simulated sour fish system.

2-Phenylethanol (2-PE) is a quorum-sensing molecule that influences microbial metabolism, but its specific role in lactic acid bacteria (LAB) fermentation remains underexplored. This study investigated the effects of 2-PE (0-750 μM) on Lactiplantibacillus pentosus 1 (Lp 1) fermentation in a simulated sour fish system. Bacterial growth, residual sugar content, organic acid profiles, and volatile flavor compounds, combined with metabolomic analysis were conducted. Results demonstrated that low to moderate concentrations of 2-PE inhibited Lp 1 growth and metabolic activity, while high concentrations induced adaptation and enhanced late-stage organic acid and amino acid metabolism. Notably, the 750 μM 2-PE treatment group exhibited the highest levels of alcohols, aldehydes, and ketones. Further analysis revealed that 2-PE primarily modulates Lp 1 fermentation via amino acid metabolism and the reductive sequence of TCA cycle. These findings suggest 2-PE as a metabolic regulator for targeted flavor enhancement in fermented fish products.