爬山虎内生菌的鉴定及其谷氨酸脱羧酶酶学特性

Identification of Parthenocissus tricuspidata endophyte and characterization of its glutamate decarboxylase

从爬山虎茎中分离到5株内生菌,其中菌株EJC-1具有谷氨酸脱羧酶(GAD)活性。当湿菌体与10 g.L-1谷氨酸钠溶液比例为1∶10(W∶V)时,在30℃和120 r.min-1下振荡反应24 h,细胞转化液中γ-氨基丁酸浓度为(3.07±0.23)mmol.L-1。通过形态特征、生理生化特征和16S rDNA序列分析鉴定EJC-1为巨大芽孢杆菌(Bacillus megateri-um)。同时基于16S rDNA构建了系统进化树,并对EJC-1进行了系统发育分析。B.megateriumEJC-1 GAD的最适反应温度和pH分别为50℃和5.6。低于40℃,GAD在pH5-6范围内较稳定。2.5 mmol.L-1Mg2+对GAD活力具有显著的促进作用,活力提高了13.85%。

One endophytic bacterium EJC - 1 producing glutamate decarboxylase （GAD） was screened from 5 strains isolated from Parthenocissus tricuspidata （ Sieb. et Zucc. ） Planch. When the biotransformation was conducted with the ratio of wet cells and 10 g·L-^1 L-glutamate at 1：10 （W： V） under 120 r· min^-1 at 30℃ for 24 h, the γ-aminobutyric acid of biotransformation solution of strain EJC -1 was （3.07 ±0. 23 ） mmol·L-^1. Base on morphological, physiological and biochemical characteristics, 16S rDNA and phylogenic analysis, the strain EJC - 1 was classified to Bacillus megaterium. The properties of its GAD were also examined, and the optimal temperature and pH for GAD activity were 50℃ and 5.6, respectively. The GAD activity was stable at pH 5 -6 and below 40 ℃. 2. 5 mmol · L-^1 Mg^2＋ significantly increased GAD activity, which promoted 13.85% of the activity.