Probiotic properties and functional potential of high-GABA Lactiplantibacillus plantarum ZG308 from Sichuan sun-dried vinegar grains (Cupei): in vitro and genomic analysis

Research on γ-aminobutyric acid (GABA) producing probiotics has garnered increasing attention, especially the search for high-yield strains. This study aimed to screen high-GABA-producing lactic acid bacteria (LAB) with functional probiotic potential from Sichuan sun-dried vinegar grains (<i>Cupei</i>) using <i>in vitro</i> and genomic analysis. In total, 90 <i>Cupei-</i>derived strains were isolated, and 19 of them were high-yield strains (3.10 ± 0.35 to 4.81 ± 0.12 g/L) without hemolytic and coagulase enzyme activity. After artificial gastric fluid challenge, three <i>Lactiplantibacillus plantarum</i> strains (ZG302, ZG307, and ZG308) with strong gastric tolerance were then subjected to comprehensive probiotic characterization. The probiotic properties of these three strains were compared, and ZG308 showed the best overall properties, with good tolerance to gastrointestinal fluids and bile, strong antibacterial activity (inhibition zone >20.5 mm), high hydrophobicity (42.49 ± 0.42%), auto-aggregation ability (98.23 ± 3.53%), strong inhibitory effects on α-glucosidase (66.77 ± 3.88%) and lipid peroxidation (44.23 ± 3.93%), efficient scavenging activity against free radicals, as well as high GABA productivity (4.46 ± 0.37 g/L). Whole-genome analysis on ZG308 further confirmed the presence of GABA production genes, the absence of toxin-encoding virulence factors and plasmid-borne antibiotic resistance genes, further underscoring its safety and probiotic potential. In conclusion, a high-GABA-producing LAB strain (ZG308) with multifunctional probiotic potential was successfully isolated from <i>Cupei</i>. The future research could explore its <i>in vivo</i> multifunctional probiotic effects.