唾液链球菌嗜热亚种Y-2产谷氨酸脱羧酶的影响因子确立

Ascertainment of Factors Affecting Glutamate Decarboxylase Production by Streptococcus Salivarius ssp. thermophilus Y-2

从产酶和细胞生长较好的MRS培养基出发,对Streptococcus salivarius ssp.thermophilus Y-2产谷氨酸脱羧酶(glutamate decarboxylase,GAD)的影响因子进行探讨,结果当培养基组成和培养条件为蛋白胨15g/L、牛肉膏12.5g/L、蔗糖12.5g/L、柠檬酸二铵2.0g/L、乙酸钠5.0g/L、K2HPO42.0g/L、CaCl2 2.0g/L、Tween 80 1.0ml、pH7.0、接种量2%(V/V)、发酵温度37℃、发酵时间12h时,较有利于菌株Y-2产GAD。Plackett-Burman设计法研究表明培养基初始pH值和K2HPO4为影响菌株Y-2产GAD的主要影响因素。经对菌株Y-2产GAD影响因素的筛选,新获得的培养基在组成上与MRS培养基相比已发生显著变化,GAD活力提高了1.3倍。

The factors affecting the glutamate decarboxylase （GAD） production by Streptococcus salivarius ssp. thermophilus Y-2 were ascertained from compostion of MRS medium which was relatively by propitious to the GAD production and the growth of cells. The results indicated that the medium that made up of 15 g/L of peptone, 12.5 g/L of beef extract, 12.5 g/L of sucrose, 2.0 g/L of ammonium dibasic citrate, 5.0 g/L of sodinm acetate, 2.0 g/L of K2HPO4, 2.0g/L of CaCl2, 1.0 ml/L of Tween 80, and initial pH 7.0 is more efficient for the GAD-production than MRS broth, and the total GAD activity is increase by 1.3 folds. The optimal inoculation percentage, temperature and time for the fermentation are 2% （V/V）, 37℃ and 12 h, respectively. Among the internal and external factors mentioned above, the initial pH 7.0 and K2HPO4 concentration are found to be the significant factors affecting the GAD-production of strain Y-2.