title: Eubacteria and archaea communities in seven mesophile anaerobic digester plants in Germany.
abstract: BACKGROUND
  Only a fraction of the microbial species used for anaerobic digestion in biogas production plants are methanogenic archaea. We have analyzed the taxonomic profiles of eubacteria and archaea, a set of chemical key parameters, and biogas production in samples from nine production plants in seven facilities in Thuringia, Germany, including co-digesters, leach-bed, and sewage sludge treatment plants. Reactors were sampled twice, at a 1-week interval, and three biological replicates were taken in each case.
  
  
  RESULTS
  A complex taxonomic composition was found for both eubacteria and archaea, both of which strongly correlated with digester type. Plant-degrading Firmicutes as well as Bacteroidetes dominated eubacteria profiles in high biogas-producing co-digesters; whereas Bacteroidetes and Spirochaetes were the major phyla in leach-bed and sewage sludge digesters. Methanoculleus was the dominant archaea genus in co-digesters, whereas Methanosarcina and Methanosaeta were the most abundant methanogens in leachate from leach-bed and sewage sludge digesters, respectively.
  
  
  CONCLUSIONS
  This is one of the most comprehensive characterizations of the microbial communities of biogas-producing facilities. Bacterial profiles exhibited very low variation within replicates, including those of semi-solid samples; and, in general, low variation in time. However, facility type correlated closely with the bacterial profile: each of the three reactor types exhibited a characteristic eubacteria and archaea profile. Digesters operated with solid feedstock, and high biogas production correlated with abundance of plant degraders (Firmicutes) and biofilm-forming methanogens (Methanoculleus spp.). By contrast, low biogas-producing sewage sludge treatment digesters correlated with high titers of volatile fatty acid-adapted Methanosaeta spp.
authors.affiliation: Cavanilles Institute of Biodiversity and Evolutionary Biology, Universitat de València, 46020 Valencia, Spain ; Bio H2 Energy GmbH, Im Steinfeld 10, 07751 Jena, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Abendroth
authors.affiliation: Cavanilles Institute of Biodiversity and Evolutionary Biology, Universitat de València, 46020 Valencia, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Vilanova
authors.affiliation: Eurofins Umwelt Ost GmbH, Löbstedter Straße 78, 07749 Jena, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Günther
authors.affiliation: Bio H2 Energy GmbH, Im Steinfeld 10, 07751 Jena, Germany ; BioEnergie Verbund e.V., Im Steinfeld 10, 07751 Jena, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Luschnig
authors.affiliation: Cavanilles Institute of Biodiversity and Evolutionary Biology, Universitat de València, 46020 Valencia, Spain ; Fundació General de la Universitat de València, València, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Porcar
keywords: Anaerobic digesters; Archaea; Biogas; Eubacteria; Methanogens