Bacillus subtilis NX-2合成γ-聚谷氨酸的立体构型调控机理  

Regulation of Stereochemical Composition of Poly-γ-glutamic Acid in Bacillus subtilis NX-2

作　　者：吴群[1] 徐虹[1] 许琳[1] 

机构地区：[1]南京工业大学制药与生命科学学院,江苏南京210009

出　　处：《过程工程学报》2006年第3期458-461,共4页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:20474029);江苏省高技术项目资助(编号:BG2005042);江苏省自然科学基金资助项目(编号:BK2004122)

摘　　要：探讨了在BacillussubtilisNX-2发酵生产γ-聚谷氨酸(γ-PGA)过程中,Mn2+对γ-PGA结构中D-和L-谷氨酸组成的影响及其与催化L-谷氨酸生成D-谷氨酸的两个相关酶-谷氨酸消旋酶和D-氨基酸转氨酶之间的关系.当Mn2+浓度由0增加到0.09g/L时,D-谷氨酸比例从18%增加到77%;谷氨酸消旋酶活性从0.200U/mg变为0.441U/mg,提高了1倍多,D-氨基酸转氨酶活性则几乎没有变化.说明谷氨酸消旋酶参与了L-到D-谷氨酸的转化过程,且Mn2+是通过改变谷氨酸消旋酶的活性来调节产物γ-PGA的立体组成的,这与目前报道的枯草芽孢杆菌合成γ-PGA过程中Mn2+浓度与γ-PGA中D-,L-构型比无关的结果不同.当Mn2+浓度为0.03g/L时,发酵过程中生成的γ-PGA中D-谷氨酸比例不变,维持在75%左右.The stereochemical composition of poly-γ-glutamic acid （γ-PGA） and glutamate racemase activity in Bacillus subtilis NX-2 were modulated by variation of Mn^2＋ concentration in the culture medium. As the concentration of Mn^2＋ varied from 0 to 0.09 g/L, the proportion of D-glutamic acid increased gradually from 18% to 77%, which was different from other γ-PGA producers in species of B. subtilis ever reported, and the glutamate racemase activity increased from 0.200 to 0.441 U/mg, while the D-amino acid aminotransferase changed a little, suggesting that glutamate racemase was involved in D-glutamic acid supply and different Mn^2＋ concentrations could change stereochemical composition of γ-PGA by regulating glutamate racemase activity. When Mn^2＋ concentration was 0.03 g/L, the proportion of D-glutamic acid remained constant throughout cultivation, approximately 75%, this was different from B. subtilis F-2-01, the stereochemical composition of T-PGA produced by the microorganism changed during cultivation.

关 键 词：Γ-聚谷氨酸 立体异构 谷氨酸消旋酶 MN^2+ 

分 类 号：Q935[生物学—微生物学] Q936