title: Discovering novel enzymes by functional screening of plurigenomic libraries from alga-associated Flavobacteriia and Gammaproteobacteria.
abstract: Alga-associated microorganisms, in the context of their numerous interactions with the host and the complexity of the marine environment, are known to produce diverse hydrolytic enzymes with original biochemistry. We recently isolated several macroalgal-polysaccharide-degrading bacteria from the surface of the brown alga Ascophyllum nodosum. These active isolates belong to two classes: the Flavobacteriia and the Gammaproteobacteria. In the present study, we constructed two "plurigenomic" (with multiple bacterial genomes) libraries with the 5 most interesting isolates (regarding their phylogeny and their enzymatic activities) of each class (Fv and Gm libraries). Both libraries were screened for diverse hydrolytic activities. Five activities, out of the 48 previously identified in the natural polysaccharolytic isolates, were recovered by functional screening: a xylanase (GmXyl7), a beta-glucosidase (GmBg1), an esterase (GmEst7) and two iota-carrageenases (Fvi2.5 and Gmi1.3). We discuss here the potential role of the used host-cell, the average DNA insert-sizes and the used restriction enzymes on the divergent screening yields obtained for both libraries and get deeper inside the "great screen anomaly". Interestingly, the discovered esterase probably stands for a novel family of homoserine o-acetyltransferase-like-esterases, while the two iota-carrageenases represent new members of the poorly known GH82 family (containing only 19 proteins since its description in 2000). These original results demonstrate the efficiency of our uncommon "plurigenomic" library approach and the underexplored potential of alga-associated cultivable microbiota for the identification of novel and algal-specific enzymes.
authors.affiliation: Microbiology and Genomics Unit, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, 5030 Gembloux, Belgium. Electronic address: Marjolaine.martin@ulg.ac.be.
authors.forename: Marjolaine
authors.initials: M
authors.lastname: Martin
authors.affiliation: Microbial Processes and Interactions, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, 5030 Gembloux, Belgium.
authors.forename: Marie
authors.initials: M
authors.lastname: Vandermies
authors.affiliation: Microbiology and Genomics Unit, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, 5030 Gembloux, Belgium.
authors.forename: Coline
authors.initials: C
authors.lastname: Joyeux
authors.affiliation: Microbiology and Genomics Unit, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, 5030 Gembloux, Belgium.
authors.forename: Renée
authors.initials: R
authors.lastname: Martin
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, Bretagne, France.
authors.forename: Tristan
authors.initials: T
authors.lastname: Barbeyron
authors.affiliation: Sorbonne Université, UPMC Univ Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff cedex, Bretagne, France.
authors.forename: Gurvan
authors.initials: G
authors.lastname: Michel
authors.affiliation: Microbiology and Genomics Unit, Gembloux Agro-Bio Tech, University of Liège, Passage des Déportés 2, 5030 Gembloux, Belgium.
authors.forename: Micheline
authors.initials: M
authors.lastname: Vandenbol
mesh_terms: D041963:Bacteroidetes / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004798:Enzymes / Q000235:genetics*; D020563:Gammaproteobacteria / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D015723:Gene Library; D005820:Genetic Testing; D000459:Phaeophyceae / Q000382:microbiology; D017422:Sequence Analysis, DNA
chemical_list: D004798:Enzymes
keywords: Agarase; Alga-associated microflora; Beta-glucosidase; Esterase; Iota-carrageenase; Kappa-carrageenase; Marine bacteria; Marine enzymes; Xylanase