title: Involvement of a novel fermentative bacterium in acidification in a thermophilic anaerobic digester.
abstract: Acidification results from the excessive accumulation of volatile fatty acids and the breakthrough of buffering capacity in anaerobic digesters. However, little is known about the identity of the acidogenic bacteria involved. Here, we identified an active fermentative bacterium during acidification in a thermophilic anaerobic digester by sequencing and phylogenetic analysis of isotopically labeled rRNA. The digestion sludge retrieved from the beginning of pH drop in the laboratory-scale anaerobic digester was incubated anaerobically at 55 °C for 4 h during which13C-labeled glucose was supplemented repeatedly.13CH4and13CO2were produced after substrate addition. RNA extracts from the incubated sludge was density-separated by ultracentrifugation, and then bacterial communities in the density fractions were screened by terminal restriction fragment length polymorphism and clone library analyses based on 16S rRNA transcripts. Remarkably, a novel lineage within the genus Thermoanaerobacterium became abundant with increasing the buoyant density and predominated in the heaviest fraction of RNA. The results in this study indicate that a thermoacidophilic bacterium exclusively fermented the simple carbohydrate glucose, thereby playing key roles in acidification in the thermophilic anaerobic digester.
authors.affiliation: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan hori-tomo@aist.go.jp.|Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Hori
authors.affiliation: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Akuzawa
authors.affiliation: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.|Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji-shi, Tokyo, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Haruta
authors.affiliation: Kajima Technical Research Institute, Chofu-shi, Tokyo, Japan.
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ueno
authors.affiliation: Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ogata
authors.affiliation: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Ishii
authors.affiliation: Department of Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, Japan.|Research Center of Bioenergy and Bioremediation, Southwest University, BeiBei District, Chongqing, China.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Igarashi
mesh_terms: D000693:Anaerobiosis; D002247:Carbon Isotopes / Q000032:analysis; D005285:Fermentation; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010802:Phylogeny; D012150:Polymorphism, Restriction Fragment Length; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000382:microbiology*; D046950:Thermoanaerobacterium / Q000145:classification* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D012336:RNA, Ribosomal, 16S; D012722:Sewage
keywords: acidification; stable isotope probing; thermophilic anaerobic digester