前体氨基酸对维生素B12发酵合成的影响

谷氨酸、苏氨酸、甘氨酸和甲硫氨酸是维生素B12合成的重要前体。在脱氮假单胞菌（Pseudomonas denitrifican）发酵的产物合成期以补加的方式考察了这4种氨基酸对维生素B12合成的影响。在合成培养基的基础上，通过单因素添加试验分别考察了这些氨基酸对维生素B12合成的影响，发现谷氨酸、甘氨酸和苏氨酸影响显著；并进一步利用三因素三水平的正交试验设计考察了氨基酸混合添加对菌体生长和维生素B12合成的影响，结果表明谷氨酸是最主要的影响因素，并且发现同时添加多种氨基酸更有利。当添加量为谷氨酸0.45 g/L、苏氨酸0.20 g/L、甘氨酸0.15 g/L时，得到的菌体量和维生素B12产量分别比对照组提高了13.1%和46.0%。

Effects of Amino Acid Precusors on Vitamin B12 Fermentation

Glutamine, threonine, glycine and methionine, crucial biosynthetic precursors for vitamin B12 production in Pseudomonas denitrifican, were fed respectively in the late fermentation phase to investigate their effects on the production of vitamin B12 by Pseudomonas denitrifican. According to the results of the single factor experiments, an orthogonal experimental design with three factors and three levels was performed. The results of the orthogonal experiments indicated that glutamine was the major factor affecting the cell growth and product formation. A combination of multiple amino acids could be more beneficial to vitamin B12 production. An increase of 13.1% in biomass and an increase of 46.0% in vitamin B12 production with the addition of 0.45 g/L glutamine, 0.20 g/L threonine and 0.15 g/L glycine into the fermentation broth.