CAJ | 학술논문

谷氨酸脱羧酶(GAD)能催化L-谷氨酸(Glu)脱羧生成γ-氨基丁酸(GABA)，而GAD和位于细胞膜上的Glu/GABA反向转运蛋白的协同作用则和一些细菌的耐酸机制有关。短乳杆菌 GAD 系统主要含有两个谷氨酸脱羧酶(GadA 和GadB)和一个Glu/GABA反向转运蛋白(GadC)。研究以Lactobacillus brevis CGMCC NO.1306为材料，在不同培养条件下，采用实时定量PCR的方法研究了酸胁迫对gadA、gadB和gadC表达的影响。实验结果表明，gadB和gadC组成操纵子，在菌体生长进入对数后期以后，低pH环境能极大地促进gadCB的表达，菌体的GAD活力主要由GadB提供且在菌体生长进入稳定期时达到最大值；相对而言，gadA的表达水平几乎不受pH环境和细胞周期的影响。以上结果将为短乳杆菌GABA发酵工艺的优化和研究酸胁迫对该菌株耐酸能力的影响提供理论指导。
곡안산탈최매(GAD)능최화L-곡안산(Glu)탈최생성γ-안기정산(GABA)，이GAD화위우세포막상적Glu/GABA반향전운단백적협동작용칙화일사세균적내산궤제유관。단유간균 GAD 계통주요함유량개곡안산탈최매(GadA 화GadB)화일개Glu/GABA반향전운단백(GadC)。연구이Lactobacillus brevis CGMCC NO.1306위재료，재불동배양조건하，채용실시정량PCR적방법연구료산협박대gadA、gadB화gadC표체적영향。실험결과표명，gadB화gadC조성조종자，재균체생장진입대수후기이후，저pH배경능겁대지촉진gadCB적표체，균체적GAD활력주요유GadB제공차재균체생장진입은정기시체도최대치；상대이언，gadA적표체수평궤호불수pH배경화세포주기적영향。이상결과장위단유간균GABA발효공예적우화화연구산협박대해균주내산능력적영향제공이론지도。
Glutamate decarboxylase (GAD) can catalyze the decarboxylation reaction ofL-glutamate (Glu) to produceγ-aminobutyric acid (GABA). The synergetic action of GAD and membrane-located Glu/GABA antiporter is related to the acid resistance of some bacterial cells under acidic conditions. The GAD system of Lactobacillus brevis is mainly comprised of two glutamate decarboxylases (GadA and GadB) and a Glu/GABA antiporter (GadC). In this study, quantitative real-time PCR was employed to investigate the effect of acid stress on the expression ofgadA,gadB andgadC inL. brevis CGMCC NO.1306 under different culture conditions. The results indicate thatgadB forms an operon withgadC and the expression ofgadCBis greatly upregulated in response to low ambient pH when cells enter late exponential growth phase. The GAD activity of cells is mainly from GadB and the highest enzyme activity is observed in the stationary growth phase. In contrast, the expression ofgadAis almost not affected by the ambient pH and cell cycle. These results will provide guidance for the optimization of GABA fermentation as well as the study on the ability of acid resistance ofL. brevis under acid stress.