The Research Of The Biosynthesis Regulation Of Vitaminb₁₂from Propionibacterium Freudenreichii

Vitamin B12 is the necessary vitamins in metabolic process of human tissue,it can prevent and treat pernicious anemia caused by lack of intrinsic factor(IF),so it is referred as"the mother of the blood",and is an important vitamins for maintaining human health.Since the chemical synthesis of Vitamin B12 requires more than 70 steps,the industrial production of Vitamin B12 by chemical methods is too difficult and expensive.With the development of gene engineering and metabolic regulation engineering technology,the productivity of Vitamin B12 in process of microbial fermentation has been greatly improved because of transform of its biosnthesis way.In an effort to increase the productivity of Vitamin B12,PCR amplification for all genes which related to the pathway of biosynthesis VB12 was carried out in this study.The expression vectors which consist of cistron or polycistron were transferred into Propionibacterium freudenreichii,and to confirm the function of genes by determining the productivity of VB12 from fermentation broth which harbored an expression vectors.Finally,we amplified the gene fragments named cbiA,cbiB,cbiC,cbiD,cbiM,cbiN and cbiQ,the expression vector which contained the gene named cbiB was constructed.This study will offer the theoretic evidences to detect the pathway of biosynthesis VB12 and to guide the modification of the strain P.freudenreichii.