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TitreStable isotope probing identifies uncultured Planctomycetes as primary degraders of a complex heteropolysaccharide in soil
AuteurWang, X; Sharp, C; Jones, G; Grasby, S E; Brady, A; Dunfield, P
SourceApplied and Environmental Microbiology vol. 81, no. 14, 2015 p. 4607-4615, https://doi.org/10.1128/aem.00055-15
Année2015
Séries alt.Secteur des sciences de la Terre, Contribution externe 20150046
ÉditeurAmerican Society for Microbiology
Documentpublication en série
Lang.anglais
DOIhttps://doi.org/10.1128/aem.00055-15
Mediapapier; en ligne; numérique
Formatspdf
Sujetsétudes des isotopes stables; études pédologiques; Bactérie
Illustrationstables; graphs; diagrams
ProgrammeCaractérisation des réservoirs de schiste, Les géosciences pour les nouvelles sources d'énergie
Résumé(disponible en anglais seulement)
Exopolysaccharides (EPS) produced by some bacteria are potential growth substrates for other bacteria in soil. We used stable isotope probing (SIP) to identify aerobic soil bacteria that assimilated carbon from cellulose produced by Gluconacetobacter xylinus, or from EPS produced by Beijerinckia indica. The latter is a heteropolysaccharide comprised primarily of L-guluronic acid, D-glucose, and D-glycero-D-mannoheptose. 13C-labeled EPS and 13C-labeled cellulose were purified from bacterial cultures grown on 13C-glucose. Two soils were incubated with these substrates, and bacteria actively assimilating them were identified via pyrosequencing of 16S rRNA genes recovered from 13C-labeled DNA. Cellulose-C was assimilated primarily by soil bacteria closely related (93-100% 16S rRNA gene sequence identities) to known cellulose-degrading bacteria. However, B. indica EPS was assimilated primarily by bacteria with low identities (80-95%) to known species, particularly by different members of the phylum Planctomycetes. In one incubation Planctomycetes made up >60% of all reads in the labeled DNA and were only distantly related (<85% identity) to any described species. Although it is impossible with SIP to completely distinguish primary polysaccharide hydrolysers from bacteria growing on produced oligo- or monosaccharides, the predominance of Planctomycetes suggested that they were primary degraders of EPS. Other bacteria assimilating B. ndica EPS included members of the Verrucomicrobia, candidate division OD1, and Armatimonadetes. The results indicate that some uncultured bacteria in soils may be adapted to using complex heteropolysaccharides for growth, and suggest that use of these substrates may provide a means for culturing new species.
Résumé(Résumé en langage clair et simple, non publié)
Les études sur les microbes qui décomposent la matière organique présente dans la roche sont gênées par la difficulté de cultiver ces microbes en laboratoire. Une nouvelle méthode par sondage d¿isotopes stables permet la séparation des microbes d'un échantillon en fonction de l'ncorporation sélective d'isotopes lourds de carbone dans leur cellule. L'ADN de ces microbes sélectionnés peut ensuite être analysé pour déterminer les espèces précises qui sont responsables de la décomposition de la matière organique. Ces nouvelles méthodes permettent de mieux connaître les processus microbiens qui ont cours dans les roches riches en matière organique.
GEOSCAN ID296410