Isolation of a Gamma‐Aminobutyric Acid ( GABA )‐Producing Lactiplantibacillus plantarum XBMU ‐ SN ‐23 and Optimization of Its Culture Medium Composition and Fermentation Conditions

ABSTRACT Gamma‐aminobutyric acid (GABA) is a crucial inhibitory neurotransmitter with diverse physiological functions, including the treatment of epilepsy, alleviation of anxiety, and improvement of depressive symptoms. Lactobacillus has emerged as an ideal genus for GABA biosynthesis due to its high safety, stable and controllable fermentation process, and broad application scope. In this study, a high‐yield GABA‐producing strain XBMU‐SN‐23 was isolated from Lanzhou Jiangshui and preliminarily identified as Lactiplantibacillus plantarum via 16S rDNA sequencing. The GABA yield of this strain under unoptimized conditions was 2.150 g/L. The Box–Behnken design combined with response surface methodology (RSM) was applied to optimize the medium components and fermentation conditions. The optimal medium composition was determined as: Tween 80 at 0.4% (v/v), Mg 2+ at 0.1 mg/mL, and Ca 2+ at 5 mg/mL, under which the actual GABA yield reached 2.618 g/L. The optimal fermentation parameters were an initial pH of 5, an inoculum size of 2.5%, and a fermentation time of 36 h, leading to an actual GABA yield of 3.562 g/L. After optimization, the GABA yield was increased by 65.7% compared with the unoptimized level. This study clarified the optimal culture conditions for high GABA production by L. plantarum XBMU‐SN‐23, laying a foundation for its potential application in GABA‐enriched fermented products.