title: Characterization of microbial communities in anaerobic bioreactors using molecular probes.
abstract: The microbial community structure of twenty-one single-phase and one two-phase full-scale anaerobic sewage sludge digesters was evaluated using oligonucleotide probes complementary to conserved tracts of the 16S rRNAs of phylogenetically defined groups of methanogens and sulfate-reducing bacteria. These probe results were interpreted in combination with results from traditional chemical analyses and metabolic activity assays. It was determined that methanogens in "healthy" mesophilic, single-phase sewage sludge digesters accounted for approximately 8-12% of the total community and that Methanosarcinales and Methanomicrobiales constituted the majority of the total methanogen population. Methanobacteriales and Methanococcales played a relatively minor role in the digesters. Phylogenetic groups of mesophilic, Gram-negative sulfate-reducing bacteria were consistently present at significant levels: Desulfovibrio and Desulfobulbus spp. were the dominant sulfate-reducing populations, Desulfobacter and Desulfobacterium spp. were present at lower levels, and Desulfosarcina, Desulfococcus, and Desulfobotulus spp. were absent. Sulfate reduction by one or more of these populations played a significant role in all digesters evaluated in this study. In addition, sulfate-reducing bacteria played a role in favoring methanogenesis by providing their substrates. The analysis of the two-phase digester indicated that true phase separation was not accomplished: significant levels of active methanogens were present in the first phase. It was determined that the dominant populations in the second phase were different from those in the single-phase digesters.
authors.affiliation: Department of Civil Engineering, University of Illinois at Urbana-Champaign 61801, USA.
authors.forename: L
authors.initials: L
authors.lastname: Raskin
authors.forename: D
authors.initials: D
authors.lastname: Zheng
authors.forename: M E
authors.initials: ME
authors.lastname: Griffin
authors.forename: P G
authors.initials: PG
authors.lastname: Stroot
authors.forename: P
authors.initials: P
authors.lastname: Misra
mesh_terms: D001421:Bacteria, Anaerobic / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D019149:Bioreactors; D015342:DNA Probes; D019605:Euryarchaeota / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis* / Q000235:genetics; D012722:Sewage / Q000382:microbiology*; D013431:Sulfates / Q000378:metabolism*; D014865:Waste Disposal, Fluid
chemical_list: D015342:DNA Probes; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D013431:Sulfates; D008697:Methane