Study On The Fermentation Of Vitamin K₂

Fibrinolysin producing strain is an important producer for natural vitamin K2. Thevitamin K2synthesis ability of six high fibrinolysin producing strains was detected whichwere preserved in this laboratory. Then the strain with the biggest vitamin K2production wasselected as the object of this study and the optimization procedure was further conducted. Atlast, the genes on the vitamin K2synthesis pathway were overexpressed to find the influenceof each enzyme. The main contents and conclutions were as follows:(1) Six high fibrinolysin producing strains were cultured which were preserved in thislaboratory. The vitamin K2production was then detected and the strain Y-2with the highestproduction of7.09mg·L-1was selected as the object. Based on morphological and molecularbiological identification, we deduce that the strain Y-2belong to Bacillus amyloliquefaciens.(2) The culture condition optimization procedure of Y-2was conducted for highervitamin K2production. The results showed that Y-2can synthesize more vitamin K2in staticculture condition than in shaking culture. And when the corn meal was liquefied bythermostable amylase, the liquifact was very suitable for the synthesis of vitamin K2. After sixdays of static culture, the concentration of vitamin K-12reached67.22mg·Lfrom7.09mg·L-1,which reached the international advanced level.(3) Based on the improved spizizen transformation method, the recombinant plasmidswere successfully transformed into the wild Bacillus amyloliquefaciens Y-2. Then, six geneson the vitamin K2synthesis pathway were cloned and overexpressed in Y-2to find theinfluence of each enzyme. The results showed that overexpression of all these six genes havea positive effect on vitamin K2production, especially hep S, the production increased by38%in shaking group and48%in static group. The effect of other genes depended on the culturemode.