Molecular characterization of a first endo-acting β-1,4-xylanase of family 10 glycoside hydrolase (PsGH10A) from Pseudopedobacter saltans comb. nov.

An endo-xylanase (PsGH10A) of family 10 glycoside hydrolase from Pseudopedobacter sultans was cloned, expressed and purified. Substrate specificity analysis of PsGH10A showed activity against beta-1,4-xylans. It showed maximum activity against beechwood xylan (591 +/- 1.1 U/mg) followed by xylan (Mw. 20,000-30,000) (57.1 +/- 0.7 U/mg). PsGH10A displayed maximum activity at pH 6.0 and 40 degrees C. The enzyme was stable in the pH range, from 6.0 to 7.5 and showed thermostability up to 40 degrees C. The kinetic parameters of PsGH10A using beechwood xylan determined were K-m 6.2 mg/mL and V-max 72 U/mg. The activity of PsGH10A was 29 +/- 2.4% enhanced by 2 mM Mn2+ ions and inhibited by less than 50 +/- 1.6% by 2 mM Zn2+, Pb2+ or Cu2+ ions. The time-dependent TLC analysis of hydrolyzed products of beechwood xylan released by PsGH10A showed the release of xylose, xylobiose and xylotetraose as end products confirming the endolytic mode of action. PsGH10A hydrolyzed products of xylan and substituted xylan indicate production of series of short-chain xylooligo-saccharides and arabinoxylo-saccharides. PsGH10A also showed saccharification of AFEX pretreated poplar and sugarcane bagasse. Therefore, it can be used for various biotechnological applications such as for prebiotic xylooligosaccharides and bioethanol production from pretreated agrowaste biomass. This is the first report on beta-1,4-xylanase cloned from Pseudopedobacter sultans.