title: Identification and characterization of a new xylanase from Gram-positive bacteria isolated from termite gut (Reticulitermes santonensis).
abstract: Termites are world champions at digesting lignocellulosic compounds, thanks to cooperation between their own enzymes and exogenous enzymes from microorganisms. Prokaryotic cells are responsible for a large part of this lignocellulolytic activity. Bacterial enzyme activities have been demonstrated in the higher and the lower termite gut. From five clones of Gram-positive bacteria isolated and identified in a previous work, we constructed a genomic DNA library and performed functional screening for alpha-amylase, beta-glucosidase, and xylanase activities. One candidate, Xyl8B8, showed xylanase activity. Sequence analysis of the genomic insert revealed five complete ORFs on the cloned DNA (5746bp). Among the encoded proteins were a putative endo-1,4-beta-xylanase (XylB8) belonging to glycoside hydrolase family 11 (GH11). On the basis of sequence analyses, genomic DNA organization, and phylogenetic analysis, the insert was shown to come from an actinobacterium. The mature xylanase (mXylB8) was expressed in Escherichia coli and purified by affinity chromatography and detected by zymogram analysis after renaturing. It showed maximal xylanase activity in sodium acetate buffer, pH 5.0 at 55 °C. Its activity was increased by reducing agents and decreased by Cu(2+), some detergents, and chelating agents. Its substrate specificity appeared limited to xylan.
authors.affiliation: Unité de Biologie Animale et Microbienne, Gembloux Agro-Bio Tech, Université de Liège, B_5030 Gembloux, Belgium. christel.matteotti@ulg.ac.be
authors.forename: Christel
authors.initials: C
authors.lastname: Mattéotti
authors.forename: Julien
authors.initials: J
authors.lastname: Bauwens
authors.forename: Catherine
authors.initials: C
authors.lastname: Brasseur
authors.forename: Cédric
authors.initials: C
authors.lastname: Tarayre
authors.forename: Philippe
authors.initials: P
authors.lastname: Thonart
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Destain
authors.forename: Frédéric
authors.initials: F
authors.lastname: Francis
authors.forename: Eric
authors.initials: E
authors.lastname: Haubruge
authors.forename: Edwin
authors.initials: E
authors.lastname: De Pauw
authors.forename: Daniel
authors.initials: D
authors.lastname: Portetelle
authors.forename: Micheline
authors.initials: M
authors.lastname: Vandenbol
mesh_terms: D039903:Actinobacteria / Q000201:enzymology*; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D001483:Base Sequence; D002846:Chromatography, Affinity; D003001:Cloning, Molecular; D043364:Endo-1,4-beta Xylanases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D004795:Enzyme Stability; D041981:Gastrointestinal Tract / Q000382:microbiology; D006026:Glycoside Hydrolases; D006863:Hydrogen-Ion Concentration; D020049:Isoptera / Q000382:microbiology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D014990:Xylans / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D014990:Xylans; D006026:Glycoside Hydrolases; D043364:Endo-1,4-beta Xylanases