Affiliation:
1. Department of Geosciences, Princeton University, Princeton, New Jersey 08544
Abstract
ABSTRACT
The presence of a copper-containing dissimilatory nitrite reductase gene (
nirK
) was discovered in several isolates of β-subdivision ammonia-oxidizing bacteria using PCR and DNA sequencing. PCR primers Cunir3 and Cunir4 were designed based on published
nirK
sequences from denitrifying bacteria and used to amplify a 540-bp fragment of the
nirK
gene from
Nitrosomonas marina
and five additional isolates of ammonia-oxidizing bacteria. Amplification products of the expected size were cloned and sequenced. Alignment of the nucleic acid and deduced amino acid (AA) sequences shows significant similarity (62 to 75% DNA, 58 to 76% AA) between nitrite reductases present in these nitrifiers and the copper-containing nitrite reductase found in classic heterotrophic denitrifiers. While the presence of a nitrite reductase in
Nitrosomonas europaea
is known from early biochemical work, preliminary sequence data from its genome indicate a rather low similarity to the denitrifier
nirK
s. Phylogenetic analysis of the partial nitrifier
nirK
sequences indicates that the topology of the
nirK
tree corresponds to the 16S rRNA and
amoA
trees. While the role of nitrite reduction in the metabolism of nitrifying bacteria is still uncertain, these data show that the
nirK
gene is present in closely related nitrifying isolates from many oceanographic regions and suggest that
nirK
sequences retrieved from the environment may include sequences from ammonia-oxidizing bacteria.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Cited by
132 articles.
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