Screening and identification of microbial strains that secrete an extracellular C-7 xylosidase of taxanes

摘要

This paper reported a novel strain screen strategy for the production of C-7 xylosidase of taxane for the biotransformation of 7-xylosyl-10-deacetylpaclitaxel (7-XAP) to 10-deacetylpaclitaxel (10-DAP) using xylan as the sole carbon and energy source. The C-7 xylosidase produced by the four strains obtained was an extracellular inducible enzyme enabling the biotransformation to be carried out directly in microbial suspension cultures. The four strains were identified as Streptomyces matensi, Arthrobacter nicotianae, Achromobacter piechaudii, and Pseudomonas plecoglossicida by morphological, physiological, and genetical characteristics. Several chemicals were confirmed as activating the enzyme activity, in which magnesium acetate improved the maximal substrate concentration from 0.1 to 0.5gl super(-1) at complete transformation in S. matensi suspension cultures. The non-mucous, extracellular activity and high substrate concentration characters of S. matensi facilitate both the upstream production of the enzyme, and downstream extraction and purification of the enzyme and the product.