Selective enrichment and molecular characterization of a previously uncultured Nitrospira-like bacterium from activated sludge

Environ Microbiol. 2006 Mar;8(3):405-15. doi: 10.1111/j.1462-2920.2005.00905.x.


Previously uncultured nitrite-oxidizing bacteria affiliated to the genus Nitrospira have for the first time been successfully enriched from activated sludge from a municipal wastewater treatment plant. During the enrichment procedure, the abundance of the Nitrospira-like bacteria increased to approximately 86% of the total bacterial population. This high degree of purification was achieved by a novel enrichment protocol, which exploits physiological features of Nitrospira-like bacteria and includes the selective repression of coexisting Nitrobacter cells and heterotrophic contaminants by application of ampicillin in a final concentration of 50 microg ml(-1). The enrichment process was monitored by electron microscopy, fluorescence in situ hybridization (FISH) with rRNA-targeted probes and fatty acid profiling. Phylogenetic analysis of 16S rRNA gene sequences revealed that the enriched bacteria represent a novel Nitrospira species closely related to uncultured Nitrospira-like bacteria previously found in wastewater treatment plants and nitrifying bioreactors. The enriched strain is provisionally classified as 'Candidatus Nitrospira defluvii'.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Ampicillin / pharmacology
  • Anti-Bacterial Agents / pharmacology
  • Bacteria / classification
  • Bacteria / genetics*
  • Bacteria / isolation & purification*
  • Bacterial Physiological Phenomena
  • DNA, Bacterial / chemistry
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / chemistry
  • DNA, Ribosomal / genetics
  • Fatty Acids / analysis
  • Fatty Acids / chemistry
  • Genes, rRNA
  • In Situ Hybridization, Fluorescence
  • Microscopy, Electron
  • Nitrobacter / drug effects
  • RNA, Bacterial / analysis
  • RNA, Ribosomal, 16S / genetics
  • Sequence Analysis, DNA
  • Sewage / microbiology*
  • Water Microbiology


  • Anti-Bacterial Agents
  • DNA, Bacterial
  • DNA, Ribosomal
  • Fatty Acids
  • RNA, Bacterial
  • RNA, Ribosomal, 16S
  • Sewage
  • Ampicillin