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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 46 (2003), S. 0 
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cultivation-independent molecular approaches were used to investigate the phylogenetic composition of Archaea and the relative abundance of phylogenetically defined groups of methanogens in the leachate of a closed municipal solid waste landfill. Cloning and phylogenetic analysis of archaeal 16S rRNA gene sequences (16S rDNA) revealed that the landfill leachate harbored a diverse Archaea community, with sequence types distributed within the two archaeal kingdoms of the Euryarchaeota and the Crenarchaeota. Of the 80 clones examined, 51 were phylogenetically associated with well-defined methanogen lineages covering two major methanogenic phenotypes; 20 were related to Thermoplasma and were grouped with some novel archaeal rRNA gene sequences recently recovered from various anaerobic habitats; finally, five belonged to Crenarchaeota and were not closely related to any hitherto cultivated species. Most of the methanogen-like clones were affiliated with the hydrogenotrophic Methanomicrobiales and the methylotrophic and acetoclastic Methanosarcinales. Quantitative oligonucleotide hybridization experiments showed that methanogens in the leachate accounted for only a very small fraction of the total community (approximately 2%) and that Methanomicrobiales and Methanosarcinales constituted the majority of the total methanogenic population.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology ecology 50 (2004), S. 0 
    ISSN: 1574-6941
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: We analyzed the phylogenetic composition of bacterial community in the effluent leachate of a full-scale recirculating landfill using a culture-independent molecular approach. 16S rRNA genes were amplified directly from leachate DNA with universally conserved and Bacteria-specific rDNA primers and cloned. The clone library was screened by restriction fragment length polymorphism, and representative rDNA sequences were determined. Many bacterial sequences displaying relatively low levels of similarity to any other hitherto reported rDNA sequences were retrieved. A total of 103 bacterial sequence types were found in 195 analyzed clones. Roughly 90% of the sequence types were affiliated with low-G + C gram-positive bacteria, the Chlamydiae/Verrucomicrobia group and with the Cytophaga–Flexibacter–Bacteroides group, where the clone distribution was 53%, 21% and 19%, respectively. The other 10 sequence types represented 7% of the total clones, and they were either affiliated with well-recognized bacterial divisions Planctomycetes, Spirochaetes, Proteobacteria and Actinobacteria, or grouped within two recently proposed candidate divisions OP9 and OP11. The most frequent sequence type represented less than 10% of the total bacterial 16S rRNA gene sequences, and the 15 more frequent sequence types accounted for at least 47% of these sequences. Some rRNA gene sequences clustered with genera or taxa that were classically identified within anaerobic treatment systems. These results indicate that, despite recent expansion, our knowledge on the microbial diversity in anaerobic treatment systems is still limited.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The diversity and structure of the archaeal community in the effluent leachate from a full-scale recirculating landfill was characterized by direct 16S rRNA gene (16S rDNA) retrieval. Total-community DNA was extracted from the microbial assemblages in the landfill leachate, and archaeal 16S rDNAs were amplified with a universally conserved primer and an Archaea-specific primer. The amplification product was then used to construct a 16S rDNA clone library, and 70 randomly selected archaeal clones in the library were grouped by restriction fragment length polymorphism (RFLP) analysis. Sequencing and phylogenetic analysis of representatives from each unique RFLP type showed that the archaeal library was dominated by methanogen-like rDNAs. Represented in the kingdom of Euryarchaeota were phylotypes highly similar to the methanogenic genera Methanoculleus, Methanosarcina, Methanocorpusculum, Methanospirillum and Methanogenium, where the clone distribution was 48, 11, 3, 1 and 1, respectively. No sequences related to known Methanosaeta spp. were retrieved. Four rDNA clones were not affiliated with the known methanogenic Archaea, but instead, they were clustered with the uncultured archaeal sequences recently recovered from anaerobic habitats. Two chimeric sequences were identified among the clones analyzed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 242 (2005), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: A 16S rDNA-based molecular study was performed to determine the nature of the bacterial constituents of the leachate from a closed municipal solid waste landfill. Total community DNA was extracted and bacterial 16S rRNA genes were subsequently amplified and cloned. Recombinant rDNA clones in the library were randomly selected, and they were sequenced for a single run and then grouped. A total of 76 sequence types representing 138 randomly selected nonchimeric clones were identified. Full-length sequencing and phylogenetic analysis of the sequence types revealed that more than 90% of the screened clones were affiliated with low-G + C gram-positive bacteria (38.4%), Proteobacteria (35.5%), the Cytophaga Flexibacter Bacteroides group (11.6%), and Spirochaetes (5.1%). Minor portions were affiliated with Verrucomicrobia (2.9%), candidate division OP11 (2.2%), and the green nonsulfur bacteria, Cyanobacteria and the Deinococcus Thermus group (each 〈1.0%). Although some rDNA sequences clustered with genera or taxa that were classically identified within anaerobic treatment systems and expected with known functions, a substantial fraction of the clone sequences showed relatively low levels of similarity with any other reported rDNA sequences and thus were derived from unknown taxa. These results suggest that bacterial communities in landfill environment are far more complex than previously expected and remain largely unexplored.
    Type of Medium: Electronic Resource
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