Affiliation:
1. Lehrstuhl für Mikrobiologie, Technische Universität München, D-85350 Freising,1
2. Institut für allgemeine Botanik, Abteilung Mikrobiologie, Universität Hamburg, D-22609 Hamburg,2 Germany
Abstract
ABSTRACT
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.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
944 articles.
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