Improvement of adenosylcobalamin production by metabolic control strategy in Propionibacterium freudenreichii.

An efficient metabolic control approach was developed to improve the industrial anaerobic fermentation of adenosylcobalamin (ado-cbl) by Propionibacterium freudenreichii. The effects of 5,6-dimethylbenzimidazole (DMB) on cell growth and ado-cbl biosynthesis were investigated. Subsequently, the results obtained from the batch culture showed that an important intermediate of ado-cbl separated from the cell extract was identified as adenosylcobinamide (ado-cbi) by high-performance liquid chromatography coupled to an ultraviolet diode array detector and ESI mass spectrometry analysis. Ado-cbi can be converted to ado-cbl when linked to DMB, which is an essential compound for ado-cbi bioconversion. This key ado-cbi is useful not only in determining ado-cbl concentration in the fermentation process but also in serving as an effective compound to guide DMB incorporation for the harvest of the maximum ado-cbl concentration. Accordingly, with scaling up to 100 L fermentation, the experimental results showed that the discrepancy was less than 1 % using the developed prediction technique. Overall, the findings show that the method is efficient in evaluating the fermentation of ado-cbl by propionibacteria.