Cloning and expression of a novel, moderately thermostable xylanase-encoding gene ( Cflxyn11A) from Cellulomonas flavigena

Abstract

The Cfl xyn11A gene, encoding the endo-1,4-β-xylanase Cfl Xyn11A from Cellulomonas flavigena, was isolated from a genomic DNA library. The open reading frame of the Cfl xyn11A gene was 999 base pairs long and encoded a polypeptide ( Cfl Xyn11A) of 332 amino acids with a calculated molecular mass of 35,110 Da. The Cfl xyn11A gene was expressed in Escherichia coli and the recombinant enzyme, with an estimated molecular weight of 31 kDa was purified and xylanase activity was measured. Cfl Xyn11A showed optimal activity at pH 6.5 and 55 °C. The enzyme demonstrated moderate thermal stability as Cfl Xyn11A maintained 50% of its activity when incubated at 55 °C for 1 h or at 45 °C for 6 h. This is the first report describing the cloning, expression and functional characterization of an endo-1,4-β-xylanase-encoding gene from C. flavigena. Cfl Xyn11A may be suitable for industrial applications in the food and feed industries, or in the pre-treatment of lignocellulosic biomass required to improve the yields of fermentable sugars for bioethanol production.