PROCESS FOR PRODUCING VITAMIN B12 BY THE FERMENTATION TECHNIQUE, AND VITAMIN B12-PRODUCING MICROORGANISM

摘要

A process for producing vitamin B12 by the fermentation technique which comprises cultivating a vitamin B12-producing microorganism belonging to the genus Propionibacterium in a culture medium containing a carbon source and a nitrogen source, and collecting vitamin B12 accumulated in the cells of the microorganism; characterized in that (1) the cultivation is carried out while adding an alkali at suitable times to the cultivation system so that during the cultivation, the cultivation system is maintained at a pH in the range of about 5 to about 7.5, and (2) the cultivation is carried out while adding a carbon source portionwise to the cultivation system nearly at the same time as the addition of the alkali, (3) provided that when a vitamin B12-producing microorganism having resistance to propionic acid is used as the microorganism, the portionwise addition of the carbon source in (2) can be omitted. Also disclosed are propionic acid-resistant, vitamin B12-producing microorganism of the genus Propionibacterium.