Comparative Analysis\nof <i>N</i>‑Lactoyl-phenylalanine\nand 3‑Phenyllactic Acid Production in Lactic Acid Bacteria\nfrom Kimchi: Metabolic Insights and Influencing Factors

<i>N</i>-Lactoyl-phenylalanine (Lac-Phe) is\na metabolite\nknown for its appetite-suppressing and antiobesity properties, while\nphenyllactic acid (PLA) is recognized for its antibacterial activity.\nBoth metabolites are derived from phenylalanine and lactic acid metabolism\nthrough peptidase and dehydrogenase activities. The aim of this study\nwas to investigate the production of Lac-Phe and PLA in kimchi, focusing\non the role of lactic acid bacteria (LAB). Ultrahigh performance liquid\nchromatography coupled with time-of-flight mass spectrometry was used\nto quantify these metabolites in homemade and commercial kimchi. Lac-Phe\nand PLA were detected in both kimchi sample types. Various genera,\nincluding <i>Lactobacillus</i>, <i>Leuconostoc</i>, and <i>Weissella,</i> were evaluated for Lac-Phe and\nPLA production. LAB strains exhibiting high Lac-Phe production generally\nshowed lower PLA production, indicating an inverse relationship between\nthese two metabolites. Analysis of dipeptidase sequences revealed\nthat the presence of carnosine dipeptidase 2 (CNDP2)-like M20 metallopeptidase\nis crucial for Lac-Phe production in LAB. Additionally, phenylalanine\nwas identified as a major factor for both Lac-Phe and PLA production,\nwhereas lactic acid supplementation did not significantly affect their\nproduction levels.