fig1

Figure 1. Screening of representative GABA-producing Lactococcus lactis strains. (A) A phylogenetic tree of Lactococcus lactis strains was constructed using the approximately-maximum-likelihood method. Strains from the Culture Collections of Food Microbiology at Jiangnan University are indicated in different colors, highlighting their positions and evolutionary branches within the tree; (B) ANI among Lactococcus lactis strains in the strain collection; (C and D) Phylogenetic analysis of GadB and GadC gene sequences in Lactococcus lactis strains from Jiangnan University; (C) Phylogenetic tree based on GadB sequences; (D) phylogenetic tree based on GadC sequences. Colored branches indicate the clustering and distribution of GABA-producing strains; (E) Qualitative assessment of GABA production by Lactococcus lactis strains using TLC; (F) Quantitative determination of GABA production in TLC-identified positive strains using ANI. GABA: Gamma-aminobutyric acid; TLC: thin-layer chromatography; HPLC: high-performance liquid chromatography; ANI: average nucleotide identity.