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Media type:
E-Article
Title:
In Situ Characterization of Nitrospira -Like Nitrite-Oxidizing Bacteria Active in Wastewater Treatment Plants
Contributor:
Daims, Holger;
Nielsen, Jeppe L.;
Nielsen, Per H.;
Schleifer, Karl-Heinz;
Wagner, Michael
imprint:
American Society for Microbiology, 2001
Published in:Applied and Environmental Microbiology
Language:
English
DOI:
10.1128/aem.67.11.5273-5284.2001
ISSN:
1098-5336;
0099-2240
Origination:
Footnote:
Description:
<jats:title>ABSTRACT</jats:title>
<jats:p>
Uncultivated
<jats:italic>Nitrospira</jats:italic>
-like bacteria in different biofilm and activated-sludge samples were investigated by cultivation-independent molecular approaches. Initially, the phylogenetic affiliation of
<jats:italic>Nitrospira</jats:italic>
-like bacteria in a nitrifying biofilm was determined by 16S rRNA gene sequence analysis. Subsequently, a phylogenetic consensus tree of the
<jats:italic>Nitrospira</jats:italic>
phylum including all publicly available sequences was constructed. This analysis revealed that the genus
<jats:italic>Nitrospira</jats:italic>
consists of at least four distinct sublineages. Based on these data, two 16S rRNA-directed oligonucleotide probes specific for the phylum and genus
<jats:italic>Nitrospira</jats:italic>
, 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
<jats:italic>Nitrospira</jats:italic>
-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
<jats:italic>Nitrospira</jats:italic>
microcolonies were detected that were water permeable, as demonstrated by fluorescein staining. The uptake of different carbon sources by
<jats:italic>Nitrospira</jats:italic>
-like bacteria within their natural habitat under different incubation conditions was studied by combined FISH and microautoradiography. Under aerobic conditions, the
<jats:italic>Nitrospira</jats:italic>
-like bacteria in bioreactor samples took up inorganic carbon (as HCO
<jats:sub>3</jats:sub>
<jats:sup>−</jats:sup>
or as CO
<jats:sub>2</jats:sub>
) 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
<jats:italic>Nitrospira</jats:italic>
-like bacteria of any of the carbon sources tested was observed under anoxic or anaerobic conditions.
</jats:p>