A nirK -cbb3 genomic region links SAR11 to nitrogen loss in the northern Benguela Upwelling System

Robert M Morris; Timothy E Mattes; Kunmanee Bubphamanee; Mike C Sadler; Luke A Calderaro; Jen Karolewski; Karen L Casciotti; Olivia U Mason

doi:10.1099/mgen.0.001620

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A nirK -cbb3 genomic region links SAR11 to nitrogen loss in the northern Benguela Upwelling System

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A nirK -cbb3 genomic region links SAR11 to nitrogen loss in the northern Benguela Upwelling System

Robert M Morris, Timothy E Mattes, Kunmanee Bubphamanee, Mike C Sadler, Luke A Calderaro, Jen Karolewski, Karen L Casciotti and Olivia U Mason

Microbial genomics, Vol.12(1), 001620

01/2026

DOI: 10.1099/mgen.0.001620

PMCID: PMC12816887

PMID: 41553858

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Abstract

Denitrification leads to nitrogen loss from marine oxygen minimum zones. The complete metabolic pathway for denitrification reduces nitrate to dinitrogen gas in four sequential steps. Many facultatively anaerobic bacteria are capable of the initial step of nitrate reduction to nitrite. Far fewer contribute to nitrogen loss by reducing nitrite to nitric oxide, nitrous oxide or dinitrogen gas. We sequenced the genomes of 24 bacteria isolated from low-oxygen waters (23 µM) in the northern Benguela Upwelling System (nBUS) to identify species with the genetic potential for denitrification. Most isolates have the genetic potential for partial denitrification, including ten SAR11 strains with a genomic region that codes for a copper-containing nitrite reductase (NirK) and a high-affinity cbb3-type cytochrome c oxidase. Evidence that nBUS SAR11 have the potential to respire nitrite in low-dissolved-oxygen waters suggests that they could have a more direct role in marine nitrogen loss.

Bacteria - classification

Bacteria - genetics

Bacteria - isolation & purification

Bacteria - metabolism

Bacterial Proteins - genetics

Bacterial Proteins - metabolism

Denitrification - genetics

Electron Transport Complex IV - genetics

Electron Transport Complex IV - metabolism

Genome, Bacterial

Nitrates - metabolism

Nitrite Reductases - genetics

Nitrite Reductases - metabolism

Nitrites - metabolism

Nitrogen - metabolism

Phylogeny

Seawater - microbiology

Details

Title: Subtitle: A nirK -cbb3 genomic region links SAR11 to nitrogen loss in the northern Benguela Upwelling System
Creators: Robert M Morris - University of Washington
Timothy E Mattes - University of Iowa
Kunmanee Bubphamanee - University of Washington
Mike C Sadler - University of Washington
Luke A Calderaro - Stanford University
Jen Karolewski - Stanford University
Karen L Casciotti - Stanford University
Olivia U Mason - Florida State University
Resource Type: Journal article
Publication Details: Microbial genomics, Vol.12(1), 001620
DOI: 10.1099/mgen.0.001620
PMID: 41553858
PMCID: PMC12816887
NLM abbreviation: Microb Genom
ISSN: 2057-5858
eISSN: 2057-5858
Publisher: Micriobiology Society
Language: English
Date published: 01/2026
Academic Unit: Civil and Environmental Engineering
Record Identifier: 9985130056002771

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