| 摘要 |
PURPOSE:To enable to produce a specific propionic acid-resistant vitamin B12- producing bacterium by subjecting specified vitamin B12-producing parent strain bacteria belonging to the genus Propionibacterium to antificial and natural mutation treatments. CONSTITUTION:Specific vitamin B12-producing parent strain bacteria belonging to the genus Propionibacterium are subjected to an antificial mutation-inducing treatment comprising the irradiation of radiations such as UV rays or using an artificial mutation-inducing agent such as nitroquanidine, and the surving bacteria are subsequently subjected further to a natural mutation-inducing treatment wherein the bacteria are culture in a liquid medium containing a carbon source, a nitrogen source and propionic acid in a concentration larger than the minimum concentration for inhibiting the growth of the parent strain bacteria. A propionic acid-resistant vitamin B12-producing bacterium producing a desired amount of the vitamin B12, such as Propionibacterium shermanii NOC 11012 [FERM BP-86], is thus produced. The culturing of the bacterium permits to seperate and collect the vitamin B12 accumulated in the bacterial cells. |
