Investigation of Vitamin D₂ and Vitamin D₃ Hydroxylation by Kutzneria albida

The active vitamin D metabolites 25-OH-D and 1α,25-(OH)₂ -D play an essential role in controlling several cellular processes in the human body and are potentially effective in the treatment of several diseases, such as autoimmune diseases, cardiovascular diseases and cancer. The microbial synthesis of vitamin D₂ (VD₂ ) and vitamin D₃ (VD₃ ) metabolites has emerged as a suitable alternative to established complex chemical syntheses. In this study, a novel strain, Kutzneria albida, with the ability to form 25-OH-D₂ and 25-OH-D₃ was identified. To further improve the conversion of the poorly soluble substrates, several solubilizers were tested. 100-fold higher product concentrations of 25-OH-D₃ and tenfold higher concentrations of 25-OH-D₂ after addition of 5 % (w/v) 2-hydroxypropyl β-cyclodextrin (2-HPβCD) were reached. Besides the single-hydroxylation products, the human double-hydroxylation products 1,25-(OH)₂ -D₂ and 1,25-(OH)₂ -D₃ and various other potential single- and double-hydroxylation products were detected. Thus, K. albida represents a promising strain for the biotechnological production of VD₂ and VD₃ metabolites.