Methylotrophic bacteria with cobalamin-dependent mutases in primary metabolism as potential strains for vitamin B12 production

Several bacterial species are known for their ability to synthesize vitamin B-12 but biotechnological vitamin B-12 production today is restricted to Pseudomonas denitrificans and Propionibacterium freudenreichii. Nevertheless, the rising popularity of veganism leads to a growing demand for vitamin B-12 and thereby interest in alternative strains which can be used as efficient vitamin B-12 sources. In this work, we demonstrate that methylotrophic microorganisms which utilize the ethylmalonyl-CoA pathway containing B-12-dependent enzymes are capable of active vitamin B-12 production. Several bacteria with an essential function of the pathway were tested for vitamin B-12 synthesis. Among the identified strains, Hyphomicrobium sp. DSM3646 demonstrated the highest vitamin B-12 levels reaching up to 17.9 +/- 5.05 mu g per g dry cell weight. These relatively high vitamin B-12 concentrations achieved in simple cultivation experiments were performed in a mineral methanol medium, which makes Hyphomicrobium sp. DSM3646 a new promising cobalamin-producing strain.