Production and characterization of exopolysaccharide and whole-genome analysis of Leuconostoc mesenteroides LmPQ23 isolated from pulque

Leuconostoc mesenteroides is a lactic acid bacterium recognized for exopolysaccharide (EPS) production, but comparative studies have revealed substantial strain-level diversity in biosynthetic potential and functional traits. Despite its ecological relevance in pulque, integrated genomic and functional characterization of native isolates remains limited. A native pulque isolate, L. mesenteroides named LmPQ23, was characterized using comparative genomics and phenotypic analyses. Genome sequencing confirmed its taxonomic identity and revealed an open pangenome, with strain-specific and accessory genes associated with carbohydrate metabolism, stress tolerance, and environmental adaptation. No acquired antibiotic resistance genes were identified, supporting the biotechnological safety of the strain. As complementary evidence of its biotechnological potential, comparative genomic analysis identified an expanded repertoire of five GH70 glucansucrases, the largest identified among the L. mesenteroides genomes analyzed, and antiSMASH detected a class IIb bacteriocin-related biosynthetic cluster. Under selected conditions, LmPQ23 produced 37.4 g/L of EPS which was structurally characterized as a branched dextran-type α-glucan with approximately 18% α-(1→3) branching. The cell-free supernatant exhibited antimicrobial activity against Gram-positive and Gram-negative indicator bacteria, associated with organic acids and a low-molecular-weight peptide fraction. GC-MS analysis identified several volatile metabolites, including compounds previously reported to exhibit antimicrobial, antioxidant, and insecticidal activities. LmPQ23 combines an open pangenome, an absence of acquired antibiotic resistance genes, an expanded glucansucrase repertoire, high dextran-producing capacity, and antimicrobial potential, highlighting the genomic and functional diversity of pulque-associated L. mesenteroides . This integrated genomic and phenotypic characterization supports the biotechnological safety and potential of LmPQ23 and provides a foundation for future characterization of its glucansucrases and antimicrobial peptides.