Shi Feng, Xu Zhinan, Cen Peilin
Institute of Bioengineering, Department of Chemical Engineering and Bioengineering, Zhejiang University, Hangzhou 310027, China.
Appl Biochem Biotechnol. 2006 Jun;133(3):271-82. doi: 10.1385/abab:133:3:271.
A strain with high poly-gamma-glutamic acid (gamma-PGA) production was isolated from fermented bean curd, a traditional Chinese food. The strain was named Bacillus subtilis ZJU-7 according to 16s rDNA sequencing and its taxonomic characters. The culture conditions for gamma-PGA production were evaluated. The most suitable carbon and nitrogen sources were sucrose and tryptone, respectively. Exogenous L-glutamic acid was necessary for gamma-PGA production, and the production of gamma-PGA increased on the addition of L-glutamic acid to the medium. In the medium containing 60 g/L of sucrose, 60 g/L of tryptone, 80 g/L of L-glutamic acid, and 10 g/L of NaCl, the yield of gamma-PGA reached 54.4 g/L after cultivation at 37 degrees C for 24 h, which was the highest gamma-PGA production compared with values reported in the literature. The average molecular mass of gamma-PGA produced was about 1.24 x 106 Daltons. B. subtilis ZJU-7 is genetically stable and can synthesize levan instead of gamma-PGA without the addition of L-glutamic acid to the medium.
从中国传统食品腐乳中分离出一株高产聚γ-谷氨酸（γ-PGA）的菌株。根据16s rDNA测序及其分类学特征，该菌株被命名为枯草芽孢杆菌ZJU-7。对γ-PGA生产的培养条件进行了评估。最适合的碳源和氮源分别是蔗糖和胰蛋白胨。外源L-谷氨酸是γ-PGA生产所必需的，向培养基中添加L-谷氨酸可提高γ-PGA的产量。在含有60 g/L蔗糖、60 g/L胰蛋白胨、80 g/L L-谷氨酸和10 g/L NaCl的培养基中，37℃培养24 h后，γ-PGA产量达到54.4 g/L，这是与文献报道值相比最高的γ-PGA产量。所产生的γ-PGA的平均分子量约为1.24×106道尔顿。枯草芽孢杆菌ZJU-7遗传稳定，在培养基中不添加L-谷氨酸时可合成果聚糖而非γ-PGA。
