益生菌是对人体健康具有促进作用的活性微生物，具有食用安全性。从酸乳制品中筛选出一株具有产γ-氨基丁酸能力较高的菌株，经形态学观察、生理生化检验和16S rDNA 序列分析，初步鉴定为短乳杆菌（Lactobacillus brevis），属益生菌范畴。经培养基和发酵条件优化，发酵液中γ-氨基丁酸的含量可达2.03 g/L。以该菌株为出发菌株进行紫外诱变处理，得到一株突变菌株，γ-氨基丁酸产量达2.31 g/L，与出发菌株相比提高了11.4%。经过多次传代，稳定性较好。研究结果有助于拓宽益生菌产品应用领域。

Probiotics are live micro-organisms with edible safety and beneficial to human health. A γ-aminobutyric acid (GABA) producing strain was isolated from yogurt samples. Based on 16S rDNA sequence, phylogenetic analysis, morphological and physiological characterization, the strain was identified as Lactobacillus brevi, which belongs to the category of probiotics. The yield of GABA reached 2.03 g/L after optimization of culture conditions and media components. Ultraviolet irradiation was used to treat the original strain. The accumulation of GABA was 2.31 g/L, which was increased 11.4% compared with that of original strain. The mutant GABA-producing strain was stable after several generations. These results showed that the application field of probiotic products could be broadened.