Affiliation:
1. School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
Abstract
ABSTRACT
Desulfovibrio desulfuricans
strain 27774 is one of a relative small group of sulfate-reducing bacteria that can also grow with nitrate as an alternative electron acceptor, but how nitrate reduction is regulated in any sulfate-reducing bacterium is controversial. Strain 27774 grew more rapidly and to higher yields of biomass with nitrate than with sulfate or nitrite as the only electron acceptor. In the presence of both sulfate and nitrate, sulfate was used preferentially, even when cultures were continuously gassed with nitrogen and carbon dioxide to prevent sulfide inhibition of nitrate reduction. The
napC
transcription start site was identified 112 bases upstream of the first base of the translation start codon. Transcripts initiated at the
napC
promoter that were extended across the
napM-napA
boundary were detected by reverse transcription-PCR, confirming that the six
nap
genes can be cotranscribed as a single operon. Real-time PCR experiments confirmed that
nap
operon expression is regulated at the level of mRNA transcription by at least two mechanisms: nitrate induction and sulfate repression. We speculate that three almost perfect inverted-repeat sequences located upstream of the transcription start site might be binding sites for one or more proteins of the CRP/FNR family of transcription factors that mediate nitrate induction and sulfate repression of nitrate reduction by
D. desulfuricans
.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
37 articles.
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