In this study, a whole-cell approach is used for biocatalytic 25OH-VitAMIN D3 synthesis, in which a molybdenum-dependent steroid C25 dehydrogenase was produced in the denitrifying bacterium Thauera aromatica under semi-aerobic conditions, where the activity of the enzyme remained stable. This enzyme uses water as a highly selective Vitamin D3 hydroxylating agent and is independent of an electron donor system. High density suspensions of resting cells producing steroid C25 dehydrogenase catalysed the conversion of Vitamin D3 to 25OH-Vitamin D3 using either O2 via the endogenous respiratory chain or externally added ferricyanide as low cost electron acceptor. The maximum 25OH-Vitamin D3 titer achieved was 1.85 g L–1 within 50 h with a yield of 99%, which is 2.2 times higher than the highest reported value obtained with previous biocatalytic systems. In addition, we developed a simple method for the recycling of the costly Vitamin D3 solubiliser hydroxypropyl beta-cyclodextrin, which could be reused for 10 reaction cycles without a significant loss of quality or quantity.
Kosian, D., Willistein, M., Weßbecher, R. et al. Highly selective whole-cell 25-hydroxyvitamin D3 synthesis using molybdenum-dependent C25-steroid dehydrogenase and cyclodextrin recycling. Microb Cell Fact 23, 30 (2024). https://doi.org/10.1186/s12934-024-02303-6