title: A pyrosequencing-based metagenomic study of methane-producing microbial community in solid-state biogas reactor.
abstract: BACKGROUND
  A solid-state anaerobic digestion method is used to produce biogas from various solid wastes in China but the efficiency of methane production requires constant improvement. The diversity and abundance of relevant microorganisms play important roles in methanogenesis of biomass. The next-generation high-throughput pyrosequencing platform (Roche/454 GS FLX Titanium) provides a powerful tool for the discovery of novel microbes within the biogas-generating microbial communities.
  
  
  RESULTS
  To improve the power of our metagenomic analysis, we first evaluated five different protocols for extracting total DNA from biogas-producing mesophilic solid-state fermentation materials and then chose two high-quality protocols for a full-scale analysis. The characterization of both sequencing reads and assembled contigs revealed that the most prevalent microbes of the fermentation materials are derived from Clostridiales (Firmicutes), which contribute to degrading both protein and cellulose. Other important bacterial species for decomposing fat and carbohydrate are Bacilli, Gammaproteobacteria, and Bacteroidetes (belonging to Firmicutes, Proteobacteria, and Bacteroidetes, respectively). The dominant bacterial species are from six genera: Clostridium, Aminobacterium, Psychrobacter, Anaerococcus, Syntrophomonas, and Bacteroides. Among them, abundant Psychrobacter species, which produce low temperature-adaptive lipases, and Anaerococcus species, which have weak fermentation capabilities, were identified for the first time in biogas fermentation. Archaea, represented by genera Methanosarcina, Methanosaeta and Methanoculleus of Euryarchaeota, constitute only a small fraction of the entire microbial community. The most abundant archaeal species include Methanosarcina barkeri fusaro, Methanoculleus marisnigri JR1, and Methanosaeta theromphila, and all are involved in both acetotrophic and hydrogenotrophic methanogenesis.
  
  
  CONCLUSIONS
  The identification of new bacterial genera and species involved in biogas production provides insights into novel designs of solid-state fermentation under mesophilic or low-temperature conditions.
authors: Institute of Nuclear and New Energy Technology, Tsinghua University, Tsinghua Garden, Haidian District, 100084, Beijing, China.
authors: An
authors: A
authors: Li
authors: The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, No.1-7 Beichen West Road, Chaoyang District, 100101, Beijing, China.
authors: Ya'nan
authors: Y
authors: Chu
authors: The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, No.1-7 Beichen West Road, Chaoyang District, 100101, Beijing, China.
authors: Xumin
authors: X
authors: Wang
authors: The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, No.1-7 Beichen West Road, Chaoyang District, 100101, Beijing, China.
authors: Lufeng
authors: L
authors: Ren
authors: The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, No.1-7 Beichen West Road, Chaoyang District, 100101, Beijing, China.
authors: Jun
authors: J
authors: Yu
authors: Institute of Nuclear and New Energy Technology, Tsinghua University, Tsinghua Garden, Haidian District, 100084, Beijing, China.
authors: Xiaoling
authors: X
authors: Liu
authors: Institute of Nuclear and New Energy Technology, Tsinghua University, Tsinghua Garden, Haidian District, 100084, Beijing, China.
authors: Jianbin
authors: J
authors: Yan
authors: Institute of Nuclear and New Energy Technology, Tsinghua University, Tsinghua Garden, Haidian District, 100084, Beijing, China.
authors: Lei
authors: L
authors: Zhang
authors: The CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, No.1-7 Beichen West Road, Chaoyang District, 100101, Beijing, China.
authors: Shuangxiu
authors: S
authors: Wu
authors: Institute of Nuclear and New Energy Technology, Tsinghua University, Tsinghua Garden, Haidian District, 100084, Beijing, China.
authors: Shizhong
authors: S
authors: Li