title: Characterization of methanogenic Archaea in the leachate of a closed municipal solid waste landfill.
abstract: 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.
authors.affiliation: Key Laboratory of Gene Engineering of the Ministry of Education, School of Life Sciences, Zhongshan University, Guangzhou 510275, PR China.
authors.forename: Li-Nan
authors.initials: LN
authors.lastname: Huang
authors.forename: Yue-Qin
authors.initials: YQ
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Zhou
authors.forename: Shuo
authors.initials: S
authors.lastname: Luo
authors.forename: Chong-Yu
authors.initials: CY
authors.lastname: Lan
authors.forename: Liang-Hu
authors.initials: LH
authors.lastname: Qu