title: Dissecting microbial community structure and methane-producing pathways of a full-scale anaerobic reactor digesting activated sludge from wastewater treatment by metagenomic sequencing.
abstract: BACKGROUND
  Anaerobic digestion has been widely applied to treat the waste activated sludge from biological wastewater treatment and produce methane for biofuel, which has been one of the most efficient solutions to both energy crisis and environmental pollution challenges. Anaerobic digestion sludge contains highly complex microbial communities, which play crucial roles in sludge treatment. However, traditional approaches based on 16S rRNA amplification or fluorescent in situ hybridization cannot completely reveal the whole microbial community structure due to the extremely high complexity of the involved communities. In this sense, the next-generation high-throughput sequencing provides a powerful tool for dissecting microbial community structure and methane-producing pathways in anaerobic digestion.
  
  
  RESULTS
  In this work, the metagenomic sequencing was used to characterize microbial community structure of the anaerobic digestion sludge from a full-scale municipal wastewater treatment plant. Over 3.0 gigabases of metagenomic sequence data were generated with the Illumina HiSeq 2000 platform. Taxonomic analysis by MG-RAST server indicated that overall bacteria were dominant (~93%) whereas a considerable abundance of archaea (~6%) were also detected in the anaerobic digestion sludge. The most abundant bacterial populations were found to be Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria. Key microorganisms and related pathways involved in methanogenesis were further revealed. The dominant proliferation of Methanosaeta and Methanosarcina, together with the functional affiliation of enzymes-encoding genes (acetate kinase (AckA), phosphate acetyltransferase (PTA), and acetyl-CoA synthetase (ACSS)), suggested that the acetoclastic methanogenesis is the dominant methanogenesis pathway in the full-scale anaerobic digester.
  
  
  CONCLUSIONS
  In short, the metagenomic sequencing study of this work successfully dissected the detail microbial community structure and the dominated methane-producing pathways of a full-scale anaerobic digester. The knowledge garnered would facilitate to develop more efficient full-scale anaerobic digestion systems to achieve high-rate waste sludge treatment and methane production.
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing, 100124, Peoples' Republic of China. gjh@bjut.edu.cn.|Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia. gjh@bjut.edu.cn.
authors.forename: Jianhua
authors.initials: J
authors.lastname: Guo
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing, 100124, Peoples' Republic of China. pyz@bjut.edu.cn.
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Peng
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia. b.ni@awmc.uq.edu.au.
authors.forename: Bing-Jie
authors.initials: BJ
authors.lastname: Ni
authors.affiliation: Key Laboratory of Beijing for Water Quality Science and Water Environmental Recovery Engineering, Engineering Research Center of Beijing, Beijing University of Technology, Beijing, 100124, Peoples' Republic of China. hxy-hit@163.com.|Beijing Drainage Group Co., Ltd, Beijing, 100022, Peoples' Republic of China. hxy-hit@163.com.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Han
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia. l.fan@awmc.uq.edu.au.
authors.forename: Lu
authors.initials: L
authors.lastname: Fan
authors.affiliation: Advanced Water Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia. z.yuan@awmc.uq.edu.au.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000693:Anaerobiosis; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000378:metabolism; D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D019149:Bioreactors / Q000382:microbiology*; D053898:Biosynthetic Pathways / Q000235:genetics; D019641:DNA, Archaeal / Q000737:chemistry / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods; D054892:Metagenome / Q000235:genetics*; D056186:Metagenomics / Q000379:methods; D008697:Methane / Q000096:biosynthesis*; D017020:Methanosarcina / Q000235:genetics / Q000378:metabolism; D019640:Methanosarcinales / Q000235:genetics / Q000378:metabolism; D059013:Microbial Consortia / Q000235:genetics*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology*; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry / Q000382:microbiology*
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D019641:DNA, Archaeal; D004269:DNA, Bacterial; D008697:Methane; D012722:Sewage; D062065:Wastewater