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Applied and Environmental Microbiology, December 2000, p. 5368-5382, Vol. 66, No. 12
Lehrstuhl für Mikrobiologie, Technische
Universität München, D-85350
Freising,1 Institut für allgemeine
Botanik, Abteilung Mikrobiologie, Universität Hamburg, D-22609
Hamburg,2 Germany
Received 17 July 2000/Accepted 4 October 2000
The current perception of evolutionary relationships and the
natural diversity of ammonia-oxidizing bacteria (AOB) is mainly based
on comparative sequence analyses of their genes encoding the 16S rRNA
and the active site polypeptide of the ammonia monooxygenase (AmoA).
However, only partial 16S rRNA sequences are available for many AOB
species and most AOB have not yet been analyzed on the amoA
level. In this study, the 16S rDNA sequence data of 10 Nitrosomonas species and Nitrosococcus mobilis
were completed. Furthermore, previously unavailable 16S rRNA sequences
were determined for three Nitrosomonas sp. isolates and for
the gamma-subclass proteobacterium Nitrosococcus
halophilus. These data were used to revaluate the specificities
of published oligonucleotide primers and probes for AOB. In addition,
partial amoA sequences of 17 AOB, including the
above-mentioned 15 AOB, were obtained. Comparative phylogenetic
analyses suggested similar but not identical evolutionary relationships
of AOB by using 16S rRNA and AmoA as marker molecules, respectively.
The presented 16S rRNA and amoA and AmoA sequence data from
all recognized AOB species significantly extend the currently used
molecular classification schemes for AOB and now provide a more robust
phylogenetic framework for molecular diversity inventories of AOB. For
16S rRNA-independent evaluation of AOB species-level diversity in
environmental samples, amoA and AmoA sequence similarity
threshold values were determined which can be used to tentatively
identify novel species based on cloned amoA sequences.
Subsequently, 122 amoA sequences were obtained from 11 nitrifying wastewater treatment plants. Phylogenetic analyses of the
molecular isolates showed that in all but two plants only nitrosomonads
could be detected. Although several of the obtained amoA
sequences were only relatively distantly related to known AOB, none of
these sequences unequivocally suggested the existence of previously
unrecognized species in the wastewater treatment environments examined.
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Phylogeny of All Recognized Species of Ammonia Oxidizers Based on
Comparative 16S rRNA and amoA Sequence Analysis:
Implications for Molecular Diversity Surveys
*
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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