利用^(13)C标记葡萄糖分析γ-聚谷氨酸的代谢途径

Investigation of Metabolic Routes to γ-Poly(glutamic acid) by ^(13)C-labeled Glucose as Medium Carbon Source

本实验室筛选的菌株Bacillus subtilis NX-2以葡萄糖和谷氨酸共同作为碳源生产γ-聚谷氨酸(γ-PGA).为探讨这2种碳源在γ-PGA合成中的作用,在培养基中加入标记的[U-13C]-葡萄糖,检测产物γ-聚谷氨酸的核磁共振碳谱信号强度,从而计算葡萄糖代谢进入产物的量.在培养基中葡萄糖浓度为4%时,γ-PGA的碳骨架中由葡萄糖进入的比例为9%左右.当葡萄糖浓度为3%时,由葡萄糖进入γ-PGA的比例降至6%.证明葡萄糖主要用于能量代谢和菌体合成,只有少量参与γ-PGA合成,而谷氨酸为γ-PGA单体的主要来源.

Bacillus subtilis NX-2 produce was used toγ-poly（glutamic acid） （γ-PGA） with glucose and glutamic acid as medium carbon sources. To clarify the role of these carbon sources in γ-PGA synthesis, metabolic routes to γ-poly glutarnic acid were investigated using ^13C-labeled glucose as medium carbon source by detecting ^13C-NMR peak intensity. When the medium glucose concentration was 4%, the repeat units of γ-PGA formed from glucose were approximately 9%. While the medium glucose concentration was 3%, the repeat units formed from glucose fell to 6%. Glucose was mainly used to form biomass and provide adenosine tri-phosphate （ATP） for γ-PGA synthesis, while glutamic acid was the main source ofγ-PGA repeat units.