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Applied and Environmental Microbiology, November 2001, p. 5273-5284, Vol. 67, No. 11
Lehrstuhl für Mikrobiologie, Technische
Universität München, 85350 Freising,
Germany,1 and Department of
Environmental Engineering, Aalborg University, DK-9000 Aalborg,
Denmark2
Received 24 May 2001/Accepted 3 September 2001
Uncultivated Nitrospira-like bacteria in different
biofilm and activated-sludge samples were investigated by
cultivation-independent molecular approaches. Initially, the
phylogenetic affiliation of Nitrospira-like bacteria in
a nitrifying biofilm was determined by 16S rRNA gene sequence analysis.
Subsequently, a phylogenetic consensus tree of the
Nitrospira phylum including all publicly available
sequences was constructed. This analysis revealed that the genus
Nitrospira consists of at least four distinct
sublineages. Based on these data, two 16S rRNA-directed oligonucleotide
probes specific for the phylum and genus Nitrospira,
respectively, were developed and evaluated for suitability for
fluorescence in situ hybridization (FISH). The probes were used to
investigate the in situ architecture of cell aggregates of
Nitrospira-like nitrite oxidizers in wastewater
treatment plants by FISH, confocal laser scanning microscopy, and
computer-aided three-dimensional visualization. Cavities and a network
of cell-free channels inside the Nitrospira microcolonies were detected that were water permeable, as demonstrated by fluorescein staining. The uptake of different carbon sources by
Nitrospira-like bacteria within their natural habitat
under different incubation conditions was studied by combined FISH and microautoradiography. Under aerobic conditions, the
Nitrospira-like bacteria in bioreactor samples took up
inorganic carbon (as HCO3
0099-2240/01/$04.00+0 DOI: 10.1128/AEM.67.11.5273-5284.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
In Situ Characterization of
Nitrospira-Like Nitrite-Oxidizing Bacteria Active in
Wastewater Treatment Plants
or as
CO2) and pyruvate but not acetate, butyrate, and
propionate, suggesting that these bacteria can grow mixotrophically in
the presence of pyruvate. In contrast, no uptake by the
Nitrospira-like bacteria of any of the carbon sources
tested was observed under anoxic or anaerobic conditions.
*
Corresponding author. Mailing address: Lehrstuhl
für Mikrobiologie, Technische Universität München, Am
Hochanger 4, D-85350 Freising, Germany. Phone: 49 8161 71 5444. Fax: 49 8161 71 5475. E-mail:
wagner{at}mikro.biologie.tu-muenchen.de.
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