title: Purification and characterization of a GH11 xylanase from biobutanol-producing Clostridium beijerinckii G117.
abstract: Most biobutanol-producing Clostridium strains are unable to ferment polysaccharides such as cellulose and xylan due to the lack of hydrolyzing enzymes. In this study, we show that Clostridium beijerinckii G117, a newly isolated biobutanol-producing strain, expresses xylanase enzyme in the presence of 1% beechwood xylan. The xylanase activity in the medium containing actively growing culture and 1% of beechwood xylan can reach up to 2.66 U/ml after 14 h of fermentation. Using salting-out and size-exclusion chromatography, we purify the crude xylanase by 8.7-fold from the supernatant with a yield of 32.2%. This purified xylanase has a molecular weight of 22.6 kDa, making it one of the smallest reported clostridial xylanases. Conserved domain analysis reveals that the xylanase belongs to glycoside hydrolase family 11 (GH11) but lacks a carbohydrate binding domain. When beechwood xylan is used as substrate for the xylanase, majority of the products are xylo-oligosaccharide (~98%), suggesting that this is an endo-1,4-β-xylanase.
authors.affiliation: Department of Chemical and Biomolecular Engineering, National University of Singapore, Block E5 #02-09, 4 Engineering Drive 4, Singapore, 117585, Singapore.
authors.forename: Choong Hey
authors.initials: CH
authors.lastname: Ng
authors.forename: Jianzhong
authors.initials: J
authors.lastname: He
authors.forename: Kun-Lin
authors.initials: KL
authors.lastname: Yang
mesh_terms: D000440:Butanols / Q000378:metabolism*; D046970:Clostridium beijerinckii / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008970:Molecular Weight; D017434:Protein Structure, Tertiary; D014990:Xylans / Q000378:metabolism
chemical_list: D000440:Butanols; D014990:Xylans; D043364:Endo-1,4-beta Xylanases