中文摘要：

为了检测和提高乳酸菌γ-氨基丁酸（GABA）产量,本研究采用纸层析预染法分析Lactobacillus brevis BS2最佳发酵产GABA条件为：pH5.0,以葡萄糖为碳源,以大豆蛋白胨和牛肉膏为复合氮源,碳氮比为1：1,底物质量分数1%,GABA产量可达到6.32g/L。采用CTAB法提取该菌株基因组,并以此基因组为模板应用降落PCR扩增出1407bp的谷氨酸脱羧酶基因gad,将gad克隆到T载体后经测序分析发现与L.brevis strain BH2的gad具有高度的同源性,同源性达98%,证明该菌株为高产GABA的富锌短小乳酸杆菌,在工业应用方面具有很大潜力。

英文摘要：

The objectives of this work were to optimize the medium composition for improved production ofγ-aminobutyric acid （GABA） by the fermentation of Lactobacillus brevis BS2 with Zinc-enriching ability and to clone and sequence the glutamate decarboxylase （GAD） gene of this strain. GABA quantification was performed using pre-staining paper chromatography method. The optimal medium composition was determined as follows：carbon source,glucose; nitrogen source,soybean peptone plus beef extract; carbon/nitrogen ratio,1：1; and substrate concentration,1%,and the maximum GABA production reached up to 6.32 g/L under such conditions. CTAB method was used for the extraction of genomic DNA from stain BS2,and the extracted genomic DNA was used as the template for the amplification of a 1407 bp gad gene by touch down PCR. The gad gene was finally cloned into the T vector. The sequencing analysis showed that the gene had 98% homology with that of Lactobacillus brevis BH2,suggesting that the obtained target gene is the gad gene of Lactobacillus brevis.