Bioprocess development of calcitriol production from vitamin D3 for industrial application using Actinomyces hyovaginalis strain

Abstract

Different approaches were applied to optimize bioconversion of vitamin D3 into its fully active metabolite (calcitriol) using Actinomyces hyovaginalis isolate A11-2, a local soil isolate which was proven to be of a potential bioconversion activity of vitamin D3 into calcitriol. In shake flask, the study isolate could convert vitamin D3 to produce about 7 µg calcitriol per 50 ml culture medium, under the previously determined optimal bioconversion conditions. Intergeneric protoplast fusion between Bacillus species and the study isolate was applied in an attempt to construct hybrids with improved vitamin D3 bioconversion capabilities. As a result, a stable protoplast hybrid (coded V8A), constructed by fusion using protoplasts of the study isolate and B. thuringenesis, was proven to show vitamin D3 into calcitriol bioconversion ability, that was about 2.8 fold as that of the parent study isolate. The bioconversion active protein could be separated form the parent study isolate crude cell lysate, using ion exchange column chromatography. The recovered protein could convert vitamin D3 into calcitriol (30 µg/10 ml) in a reaction time of 6 h, under the optimal conditions.