title: Metagenome and metaproteome analyses of microbial communities in mesophilic biogas-producing anaerobic batch fermentations indicate concerted plant carbohydrate degradation.
abstract: Microbial communities in biogas batch fermentations, using straw and hay as co-substrates, were analyzed at the gene and protein level by metagenomic and metaproteomic approaches. The analysis of metagenomic data revealed that the Clostridiales and Bacteroidales orders were prevalent in the community. However, the number of sequences assigned to the Clostridiales order decreased during fermentation, whereas the number of sequences assigned to the Bacteroidales order increased. In addition, changes at the functional level were monitored and the metaproteomic analyses detected transporter proteins and flagellins, which were expressed mainly by members of the Bacteroidetes and Firmicutes phyla. A high number of sugar transporters, expressed by members of the Bacteroidetes, proved their potential to take up various glycans efficiently. Metagenome data also showed that methanogenic organisms represented less than 4% of the community, while 20-30% of the identified proteins were of archeal origin. These data suggested that methanogens were disproportionally active. In conclusion, the community studied was capable of digesting the recalcitrant co-substrate. Members of the Firmicutes phylum seemed to be the main degraders of cellulose, even though expression of only a few glycoside hydrolases was detected. The Bacteroidetes phylum expressed a high number of sugar transporters and seemed to specialize in the digestion of other polysaccharides. Finally, it was found that key enzymes of methanogenesis were expressed in high quantities, indicating the high metabolic activity of methanogens, although they only represented a minor group within the microbial community.
authors.affiliation: Leibniz-Institut für Agrartechnik Potsdam-Bornim e.V., Abteilung Bioverfahrenstechnik, Max-Eyth-Allee 100, 14469 Potsdam, Germany.
authors.forename: Angelika
authors.initials: A
authors.lastname: Hanreich
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schimpf
authors.forename: Martha
authors.initials: M
authors.lastname: Zakrzewski
authors.forename: Andreas
authors.initials: A
authors.lastname: Schlüter
authors.forename: Dirk
authors.initials: D
authors.lastname: Benndorf
authors.forename: Robert
authors.initials: R
authors.lastname: Heyer
authors.forename: Erdmann
authors.initials: E
authors.lastname: Rapp
authors.forename: Alfred
authors.initials: A
authors.lastname: Pühler
authors.forename: Udo
authors.initials: U
authors.lastname: Reichl
authors.forename: Michael
authors.initials: M
authors.lastname: Klocke
mesh_terms: D000693:Anaerobiosis; D056804:Biofuels; D019149:Bioreactors / Q000382:microbiology*; D058448:Biota; D001711:Biotransformation; D050260:Carbohydrate Metabolism; D005285:Fermentation; D054892:Metagenome; D010944:Plants / Q000737:chemistry*; D020543:Proteome
chemical_list: D056804:Biofuels; D020543:Proteome