title: Leachates from municipal solid waste disposal sites harbor similar, novel nitrogen-cycling bacterial communities.
abstract: High emissions of nitrous oxide (N(2)O) have recently been documented at municipal solid waste (MSW) landfills. However, the biodiversity of the bacterial populations involved remains unexplored. In this study, we investigated communities of ammonia-oxidizing bacteria (AOB) and denitrifying bacteria associated with the leachates from three MSW disposal sites by examining the diversity of the ammonia monooxygenase structural gene amoA and the nitrous oxide reductase gene nosZ, respectively. Cloning and phylogenetic analysis of the functional genes revealed novel and similar groups of prokaryotes involved in nitrogen cycling in the leachates with different chemical compositions. All amoA sequences recovered grouped within the Nitrosomonas europaea cluster in the Betaproteobacteria, with the vast majority showed only relatively moderate sequence similarities to known AOB but were exclusively most similar to environmental clones previously retrieved from wastewater treatment plants. All nosZ sequences retrieved did not cluster with any hitherto reported nosZ genes and were only remotely related to recognized denitrifiers from the Gammaproteobacteria and thus could not be affiliated. Significant overlap was found for the three denitrifying nosZ leachate communities. Our study suggests a significant selection of the novel N-cycling groups by the unique environment at these MSW disposal sites.
authors.affiliation: Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, Zhongshan University, Guangzhou, China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Zhu
authors.forename: Gilbert Y S
authors.initials: GY
authors.lastname: Chan
authors.forename: Kai-Long
authors.initials: KL
authors.lastname: Cai
authors.forename: Liang-Hu
authors.initials: LH
authors.lastname: Qu
authors.forename: Li-Nan
authors.initials: LN
authors.lastname: Huang
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D044822:Biodiversity; D003001:Cloning, Molecular; D016000:Cluster Analysis; D020563:Gammaproteobacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D005798:Genes, Bacterial; D005819:Genetic Markers; D014644:Genetic Variation; D009586:Nitrogen Fixation; D043370:Nitrosomonas europaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification; D010088:Oxidoreductases / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D012037:Refuse Disposal; D017422:Sequence Analysis, DNA; D014871:Water Microbiology; D014874:Water Pollutants, Chemical
chemical_list: D005819:Genetic Markers; D014874:Water Pollutants, Chemical; D010088:Oxidoreductases; C022763:nitrous oxide reductase; C045582:ammonia monooxygenase