title: Diversity of glycosyl hydrolases from cellulose-depleting communities enriched from casts of two earthworm species.
abstract: The guts and casts of earthworms contain microbial assemblages that process large amounts of organic polymeric substrates from plant litter and soil; however, the enzymatic potential of these microbial communities remains largely unexplored. In the present work, we retrieved carbohydrate-modifying enzymes through the activity screening of metagenomic fosmid libraries from cellulose-depleting microbial communities established with the fresh casts of two earthworm species, Aporrectodea caliginosa and Lumbricus terrestris, as inocula. Eight glycosyl hydrolases (GHs) from the A. caliginosa-derived community were multidomain endo-beta-glucanases, beta-glucosidases, beta-cellobiohydrolases, beta-galactosidase, and beta-xylosidases of known GH families. In contrast, two GHs derived from the L. terrestris microbiome had no similarity to any known GHs and represented two novel families of beta-galactosidases/alpha-arabinopyranosidases. Members of these families were annotated in public databases as conserved hypothetical proteins, with one being structurally related to isomerases/dehydratases. This study provides insight into their biochemistry, domain structures, and active-site architecture. The two communities were similar in bacterial composition but significantly different with regard to their eukaryotic inhabitants. Further sequence analysis of fosmids and plasmids bearing the GH-encoding genes, along with oligonucleotide usage pattern analysis, suggested that those apparently originated from Gammaproteobacteria (pseudomonads and Cellvibrio-like organisms), Betaproteobacteria (Comamonadaceae), and Alphaproteobacteria (Rhizobiales).
authors.affiliation: CSIC, Institute of Catalysis, 28049 Madrid, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Beloqui
authors.forename: Taras Y
authors.initials: TY
authors.lastname: Nechitaylo
authors.forename: Nieves
authors.initials: N
authors.lastname: López-Cortés
authors.forename: Azam
authors.initials: A
authors.lastname: Ghazi
authors.forename: María-Eugenia
authors.initials: ME
authors.lastname: Guazzaroni
authors.forename: Julio
authors.initials: J
authors.lastname: Polaina
authors.forename: Axel W
authors.initials: AW
authors.lastname: Strittmatter
authors.forename: Oleg
authors.initials: O
authors.lastname: Reva
authors.forename: Agnes
authors.initials: A
authors.lastname: Waliczek
authors.forename: Michail M
authors.initials: MM
authors.lastname: Yakimov
authors.forename: Olga V
authors.initials: OV
authors.lastname: Golyshina
authors.forename: Manuel
authors.initials: M
authors.lastname: Ferrer
authors.forename: Peter N
authors.initials: PN
authors.lastname: Golyshin
mesh_terms: D000818:Animals; D001419:Bacteria / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D058448:Biota; D002482:Cellulose / Q000378:metabolism*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005243:Feces / Q000382:microbiology; D015723:Gene Library; D014644:Genetic Variation; D006026:Glycoside Hydrolases / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D054892:Metagenome; D008969:Molecular Sequence Data; D009835:Oligochaeta / Q000382:microbiology*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D004269:DNA, Bacterial; D002482:Cellulose; D006026:Glycoside Hydrolases