pH值和溶解氧对枯草芽孢杆菌SK 11.004合成γ-谷氨酰转肽酶的影响。
Effects of pH and dissolved oxygen on the synthesis of γ-glutamyltranspeptidase from Bacillus subtilis SK 11.004.
作者信息
Li Weiqiao, Jiang Bo, Mu Wanmeng, Miao Ming, Zhang Tao
机构信息
State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, 214122 Wuxi, Jiangsu, China; School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, 214122 Wuxi, Jiangsu, China.
出版信息
J Sci Food Agric. 2012 Feb;92(3):475-80. doi: 10.1002/jsfa.4635. Epub 2011 Oct 10.
BACKGROUND
γ-Glutamyltranspeptidase (GGT; EC 2.3.2.2) is a widely distributed enzyme that is of interest in the food industry. In this study the effects of pH and dissolved oxygen (DO) on GGT synthesis from Bacillus subtilis SK 11.004 were investigated.
RESULTS
GGT production increased to 0.5 U mL⁻¹ when the pH value was controlled at 6.5. The control of a single DO level revealed that the highest specific growth rate (3.42 h⁻¹) and GGT production rate (0.40 U g⁻¹ mL⁻¹) were obtained at DO levels of 40 and 10% respectively. To satisfy the different oxygen demands at different stages of cell growth and GGT synthesis, a stage DO level control strategy was designed as follows: 40% from 0 to 4 h, 30% from 4 to 6 h and 10% from 6 to 18 h. Furthermore, the maximum biomass (2.27 g L⁻¹) and GGT production (3.05 U mL⁻¹) could be obtained using a fermentation strategy combining a constant pH value with stage DO level control.
CONCLUSION
The proposed fermentation strategy resulted in a 13.7-fold increase in GGT production. This finding should be of great importance for the industrial production of GGT.
背景
γ-谷氨酰转肽酶（GGT；EC 2.3.2.2）是一种广泛分布的酶，在食品工业中备受关注。本研究考察了pH值和溶解氧（DO）对枯草芽孢杆菌SK 11.004合成GGT的影响。
结果
当pH值控制在6.5时，GGT产量增加到0.5 U mL⁻¹。对单一溶解氧水平的控制表明，分别在溶解氧水平为40%和10%时获得了最高比生长速率（3.42 h⁻¹）和GGT产率（0.40 U g⁻¹ mL⁻¹）。为了满足细胞生长和GGT合成不同阶段的不同氧气需求，设计了一种阶段溶解氧水平控制策略如下：0至4小时为40%，4至6小时为30%，6至18小时为10%。此外，采用恒定pH值与阶段溶解氧水平控制相结合的发酵策略可获得最大生物量（2.27 g L⁻¹）和GGT产量（3.05 U mL⁻¹）。
结论
所提出的发酵策略使GGT产量提高了13.7倍。这一发现对GGT的工业化生产具有重要意义。
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