method for increasing the production of vitamin b12 in 2 with methanobakterien

摘要

The invention relates to a method for increasing the vitamin B12 production of fermentation processes performed in a known way with a mixed population of mesophilic methane-producing bacteria under anaerobic conditions. According to the invention in an enrichment period of preferably 4 to 7 days a nutrient concentrate containing mainly inorganic ammonium compounds as nitrogen source and mainly methanol as carbon source and having a N:C weight ratio of 1:10 to 1:20, preferably 1:11 to 1:15 is added in daily portions to a fermentation broth obtained from a usual vitamin B12 fermentation process and containing living bacterium populations so as to increase the total concentration of assimilable nitrogen by a factor of maximum 4 until the end of the enrichment period, and thereafter the fermentation is terminated and the obtained fermentation broth with an increased vitamin B12 content is processed, or the fermentation is continued by periodically removing a portion of the fermentation broth and supplementing it with a same volume of fresh nutrient medium containing mainly inorganic ammonium compounds as nitrogen source and mainly methanol as carbon source and having a N:C weight ratio of 1:10 to 1:20, preferably 1:11 to 1:15.