短乳杆菌和植物乳杆菌产γ-氨基丁酸及其关键基因的研究

Production of γ-aminobutyric acid by Lactobacillus brevis and Lactobacillus plantarum and key relevant genes analysis

为研究乳杆菌γ-氨基丁酸(γ-aminobutyric acid,GABA)的产量以及其与谷氨酸脱羧酶系统关键基因表达的相关性,实验结合GABA产量、基因组学调查和谷氨酸脱羧酶(glutamate decarboxylase,GAD)系统基因的扩增结果,发现产GABA的菌株在短乳杆菌、植物乳杆菌中分布较多,这2个种属可作为产GABA菌株的主要筛选对象.通过qRT-PCR研究短乳杆菌和植物乳杆菌不同生长时期GAD相关基因转录情况,结果表明,短乳杆菌的gadB和gadC的表达量变化情况相似,且在对数后期或稳定前期达到高峰.文中的短乳杆菌高产GABA可能与其gadC和gadB的高表达有关.植物乳杆菌的gadB表达变化与短乳杆菌类似,但是与GABA的产量之间相关性较弱,可能存在其他因素的影响.该研究为产GABA菌株的筛选,乳杆菌中GAD基因的表达调控,GABA发酵工艺的优化提供了理论基础.

This study was conducted to study differences inγ-aminobutyric acid(GABA)production in Lactobacillus and the correlation between its yield and key genes expressions in the glutamate decarboxylase(GAD)system.The results showed that most GABA-producing strains belonged to L.brevis and L.plantarum.The transcriptional activities of GAD-related genes at different growth stages of L.brevis and L.plantarum were studied by qRT-PCR.It was found that the expression levels of gadB and gadC in L.brevis were similar and peaked at late logarithm or early stable phase.Therefore,the high-yield of GABA in L.brevis may be associated with high expressions of gadC and gadB.Moreover,the expression of gadB in L.plantarum was similar to that of L.brevis,but its GABA production had little correlation with gadB expression,which indicated that other factors might affect L.plantarum producing GABA.Overall,this study provides a theoretical basis for screening GABA-producing strains and regulating GAD gene expression in Lactobacillus as well as for optimizing GABA fermentation process.