ABSTRACT
Here we report on the biodiversity and abundance of aerobic and anaerobic ammonium-oxidizing bacteria in sediment samples from the Xinyi River, Jinagsu Province (China). The biodiversity of aerobic ammonium-oxidizing bacteria in the sediment was assessed using the amoA gene as functional marker. The retrieved amoA clones were affiliated to environmental sequences from freshwater habitats. The closest cultivated relative was Nitrosomonas urea. Anaerobic ammonium-oxidizing (anammox) bacteria were studied using anammox and planctomycete-specific 16S rRNA gene primers. The sediments contained 16S rRNA genes and bacterial cells closely related to the known anammox bacterium Candidatus'Brocadia anammoxidans'. Anaerobic continuous flow reactors were set up to enrich anammox organisms from the sediments. After an adaptation period of about 25 days the reactors started to consume ammonium and nitrite, indicating that the anammox reaction was occurring with a rate of 41-58 nmol cm(-3) h(-1). Community analysis of the enrichments by quantitative fluorescence in situ hybridization showed an increase in the abundance of anammox bacteria from < 1% to 6 +/- 2% of the total population. Analysis of the 16S rRNA genes showed that the enriched anammox organisms were related to the Candidatus'Scalindua' genus.
Subject(s)
Bacteria, Aerobic/classification , Bacteria, Anaerobic/classification , Geologic Sediments/microbiology , Quaternary Ammonium Compounds/metabolism , Rivers/microbiology , Bacteria, Aerobic/genetics , Bacteria, Aerobic/metabolism , Bacteria, Anaerobic/genetics , Bacteria, Anaerobic/metabolism , Biodiversity , China , Ecosystem , Molecular Sequence Data , Phylogeny , RNA, Ribosomal, 16S/classificationABSTRACT
In situ identification of ANAMMOX bacteria was conducted using 16S rRNA approach for sediment samples from the Xinyi River in Jiangsu Province, China. 16S rRNA clone library including 6 clone sequences was constructed. The alignment of these sequences and treeing were conducted using ARB package. Results show that the sediment samples contained 16S rRNA genes closely related to the known ANAMMOX bacterium Candidatus "Brocadia anammoxidans" (similarity of 91%). They also contained 16S rRNA gene sequences from a new branch of Planctomycetes distantly related to the ANAMMOX sequence cluster. However, the microbiological characteristics of these Planctomycetes are to be studied in the future. The detection of ANAMMOX bacteria will lead to further research on ANAMMOX process in the remediation and restoration of freshwater aquatic ecosystems and new understanding of the nitrogen cycle.
