Characterization of a novel salt-, xylose- and alkali-tolerant GH43 bifunctional beta-xylosidase/alpha-L-arabinofuranosidase from the gut bacterial genome

摘要

A GH43 bifunctional beta-xylosidase encoding gene (XylRBM26) was cloned from Massilia sp. RBM26 and successfully expressed in Escherichia coli. Recombinant XylRBM26 exhibited beta-xylosidase and alpha-L-arabinofuranosidase activities. When 4-nitrophenyl-beta-D-xylopyranoside was used as a substrate, the enzyme reached optimal activity at pH 6.5 and 50 degrees C and remained stable at pH 5.0-10.0. Purified XylRBM26 presented good salt tolerance and retained 96.6% activity in 3.5 M NaCl and 77.9% initial activity even in 4.0 M NaCl. In addition, it exhibited high tolerance to xylose with Ki value of 500 mM. This study was the first to identify and characterize NaCl-tolerant beta-xylosidase/alpha-L-arabinofuranosidase from the gut microbiota. The enzyme's salt, xylose, and alkali stability and resistance to various chemicals make it a potential biocatalyst for the saccharification of lignocellulose, the food industry, and industrial processes conducted in sea water. (C) 2019, The Society for Biotechnology, Japan. All rights reserved.