title: New glucosidase activities identified by functional screening of a genomic DNA library from the gut microbiota of the termite Reticulitermes santonensis.
abstract: β-Glucosidases are widely distributed in living organisms and play a major role in the degradation of wood, hydrolysing cellobiose or cello-oligosaccharides to glucose. Termites are among the rare animals capable of digesting wood, thanks to enzyme activities of their own and to enzymes produced by their gut microbiota. Many bacteria have been identified in the guts of lower termites, some of which possess cellulolytic or/and hemicellulolytic activity, required for digesting wood. Here, having isolated bacterial colonies from the gut of Reticulitermes santonensis, we constructed in Escherichia coli a genomic DNA library corresponding to all of the colonies obtained and screened the library for clones displaying β-glucosidase activity. This screen revealed 8 positive clones. Sequence analysis with the BLASTX program revealed putative enzymes belonging to three glycoside hydrolase families (GH1, GH3 and GH4). Agar-plate tests and enzymatic assays revealed differences between the GH1- and GH3-type enzymes (as regards substrate specificity and regulation) and a difference in substrate specificity within the GH3 group. The substrate specificities and characteristic activities of these enzymes suggest that they may intervene in the depolymerisation of cellulose and hemicellulose.
authors.affiliation: Unité de Biologie Animale et Microbienne, Gembloux Agro-Bio Tech, Université de Liège, 6 Avenue Maréchal Juin, Gembloux, Belgium. christel.matteotti@ulg.ac.be
authors.forename: Christel
authors.initials: C
authors.lastname: Mattéotti
authors.forename: Philippe
authors.initials: P
authors.lastname: Thonart
authors.forename: Frédéric
authors.initials: F
authors.lastname: Francis
authors.forename: Eric
authors.initials: E
authors.lastname: Haubruge
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Destain
authors.forename: Catherine
authors.initials: C
authors.lastname: Brasseur
authors.forename: Julien
authors.initials: J
authors.lastname: Bauwens
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: D000362:Agar; D000818:Animals; D002482:Cellulose / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D041981:Gastrointestinal Tract / Q000382:microbiology; D015723:Gene Library; D020049:Isoptera / Q000382:microbiology*; D054892:Metagenome; D008969:Molecular Sequence Data; D011134:Polysaccharides / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013379:Substrate Specificity; D001617:beta-Glucosidase / Q000032:analysis* / Q000235:genetics*
chemical_list: D003470:Culture Media; D004269:DNA, Bacterial; D011134:Polysaccharides; C007916:hemicellulose; D000362:Agar; D002482:Cellulose; D001617:beta-Glucosidase