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 B₁₂ but biotechnological vitamin B₁₂ production today is restricted to Pseudomonas denitrificans and Propionibacterium freudenreichii. Nevertheless, the rising popularity of veganism leads to a growing demand for vitamin B₁₂ and thereby interest in alternative strains which can be used as efficient vitamin B₁₂ sources. In this work, we demonstrate that methylotrophic microorganisms which utilize the ethylmalonyl-CoA pathway containing B₁₂-dependent enzymes are capable of active vitamin B₁₂ production. Several bacteria with an essential function of the pathway were tested for vitamin B₁₂ synthesis. Among the identified strains, Hyphomicrobium sp. DSM3646 demonstrated the highest vitamin B₁₂ levels reaching up to 17.9 ± 5.05 µg per g dry cell weight. These relatively high vitamin B₁₂ concentrations achieved in simple cultivation experiments were performed in a mineral methanol medium, which makes Hyphomicrobium sp. DSM3646 a new promising cobalamin-producing strain.

Keywords: Vitamin B12 · Pseudovitamin B12 · Cobalamin · LC–MS · Methylotroph · Ethylmalonyl- CoA pathway