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Abstract
Objectives
To find extracellular biocatalysts that can specifically and efficiently remove the C-7 xylosyl group from 7-xylosyltaxanes.
Results
A Cellulosimicrobium cellulans strain F16 that can remove the C-7 xylosyl group from 7-xylosyltaxanes was isolated from the root soil of an old Taxus yunnanensis tree. Using corn cob as sole carbon source, the maximum 7-xylosyl-10-deacetylpaclitaxel [beta]-xylosidase activity of 9.6 U l^sup -1^ was achieved. The [beta]-xylosidase could be trapped by a ceramic tubular membrane (pore size 50 nm), and exhibited an apparent molecular weight much greater than 500 kDa. Under optimized conditions, 3.75 l cell-free culture medium transformed 2 grams 7-xylosyltaxane mixtures to their corresponding aglycones within 3 h, with a conversion >98 %.
Conclusion
This is the first report that C. cellulans can produce extracellular [beta]-xylosidases capable of removing the C-7 xylosyl group from 7-xylosyltaxanes.