Detection and phylogenetic analysis of the membrane-bound nitrate reductase (Nar) in pure cultures and microbial communities from deep-sea hydrothermal vents

Ileana Pérez-Rodríguez, Kenneth A. Bohnert, Mariola Cuebas, Ramaydalis Keddis, Costantino Vetriani

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Over the past few years the relevance of nitrate respiration in microorganisms from deep-sea hydrothermal vents has become evident. In this study, we surveyed the membrane-bound nitrate reductase (Nar) encoding gene in three different deep-sea vent microbial communities from the East Pacific Rise and the Mid-Atlantic Ridge. Additionally, we tested pure cultures of vent strains for their ability to reduce nitrate and for the presence of the NarG-encoding gene in their genomes. By using the narG gene as a diagnostic marker for nitrate-reducing bacteria, we showed that nitrate reductases related to Gammaproteobacteria of the genus Marinobacter were numerically prevalent in the clone libraries derived from a black smoker and a diffuse flow vent. In contrast, NarG sequences retrieved from a community of filamentous bacteria located about 50 cm above a diffuse flow vent revealed the presence of a yet to be identified group of enzymes. 16S rRNA gene-inferred community compositions, in accordance with previous studies, showed a shift from Alpha- and Gammaproteobacteria to Epsilonproteobacteria as the vent fluids become warmer and more reducing. Based on these findings, we argue that Nar-catalyzed nitrate reduction is likely relevant in temperate and less reducing environments where Alpha- and Gammaproteobacteria are more abundant and where nitrate concentrations reflect that of background deep seawater.

Original languageEnglish (US)
Pages (from-to)256-267
Number of pages12
JournalFEMS microbiology ecology
Volume86
Issue number2
DOIs
StatePublished - Nov 2013

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology

Keywords

  • Anaerobic respiration
  • Bacteria
  • Deep-sea
  • Hydrothermal fluids
  • Nitrate reduction
  • Nitrogen cycle

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