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Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.

Kalvelage T, Lavik G, Jensen MM, Revsbech NP, Löscher C, Schunck H, Desai DK, Hauss H, Kiko R, Holtappels M, LaRoche J, Schmitz RA, Graco MI, Kuypers MM - PLoS ONE (2015)

Bottom Line: Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms.In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters.Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

View Article: PubMed Central - PubMed

Affiliation: Biogeochemistry Department, Max Planck Institute for Marine Microbiology, Bremen, Germany.

ABSTRACT
Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

No MeSH data available.


Abundance of genes and transcripts encoding for terminal respiratory oxidases in the ETSP OMZ.(a, b) Abundance of low-affinity (cytochrome c oxidase) and high-affinity (cytochrome bd and cbb3 oxidase) aerobic oxidases in the Peruvian OMZ (station 3). (c-f) Abundance and expression of cytochrome oxidase genes in the OMZ off Chile during cruise MOOMZ-1 [34]. Taxonomic affiliations of cytochrome oxidases are shown on domain, phylum or class level if represented by at least 5% of oxidase-coding sequences. Exact abundance and expression levels as well as taxonomic assignments of the individual types of cytochrome oxidases are given in S3 Table.
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pone.0133526.g002: Abundance of genes and transcripts encoding for terminal respiratory oxidases in the ETSP OMZ.(a, b) Abundance of low-affinity (cytochrome c oxidase) and high-affinity (cytochrome bd and cbb3 oxidase) aerobic oxidases in the Peruvian OMZ (station 3). (c-f) Abundance and expression of cytochrome oxidase genes in the OMZ off Chile during cruise MOOMZ-1 [34]. Taxonomic affiliations of cytochrome oxidases are shown on domain, phylum or class level if represented by at least 5% of oxidase-coding sequences. Exact abundance and expression levels as well as taxonomic assignments of the individual types of cytochrome oxidases are given in S3 Table.

Mentions: Identification of cytochrome oxidases, catalysing the terminal electron transfer during oxic respiration, in the South Pacific OMZ provided further evidence for active aerobic respiration at near-anoxic levels of O2. Metagenomes obtained in the Peruvian offshore OMZ (station 3) as well as metagenomes and metatranscriptomes previously collected off Chile [34], revealed presence and expression of genes encoding for low-affinity cytochrome c oxidases (Km ~200 nmol O2 l-1) as well as high-affinity cytochrome bd and cbb3 oxidases (Km <10 nmol O2 l-1) [38] from the oxycline down to the OMZ core (Fig 2 and S3 Table).


Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.

Kalvelage T, Lavik G, Jensen MM, Revsbech NP, Löscher C, Schunck H, Desai DK, Hauss H, Kiko R, Holtappels M, LaRoche J, Schmitz RA, Graco MI, Kuypers MM - PLoS ONE (2015)

Abundance of genes and transcripts encoding for terminal respiratory oxidases in the ETSP OMZ.(a, b) Abundance of low-affinity (cytochrome c oxidase) and high-affinity (cytochrome bd and cbb3 oxidase) aerobic oxidases in the Peruvian OMZ (station 3). (c-f) Abundance and expression of cytochrome oxidase genes in the OMZ off Chile during cruise MOOMZ-1 [34]. Taxonomic affiliations of cytochrome oxidases are shown on domain, phylum or class level if represented by at least 5% of oxidase-coding sequences. Exact abundance and expression levels as well as taxonomic assignments of the individual types of cytochrome oxidases are given in S3 Table.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507870&req=5

pone.0133526.g002: Abundance of genes and transcripts encoding for terminal respiratory oxidases in the ETSP OMZ.(a, b) Abundance of low-affinity (cytochrome c oxidase) and high-affinity (cytochrome bd and cbb3 oxidase) aerobic oxidases in the Peruvian OMZ (station 3). (c-f) Abundance and expression of cytochrome oxidase genes in the OMZ off Chile during cruise MOOMZ-1 [34]. Taxonomic affiliations of cytochrome oxidases are shown on domain, phylum or class level if represented by at least 5% of oxidase-coding sequences. Exact abundance and expression levels as well as taxonomic assignments of the individual types of cytochrome oxidases are given in S3 Table.
Mentions: Identification of cytochrome oxidases, catalysing the terminal electron transfer during oxic respiration, in the South Pacific OMZ provided further evidence for active aerobic respiration at near-anoxic levels of O2. Metagenomes obtained in the Peruvian offshore OMZ (station 3) as well as metagenomes and metatranscriptomes previously collected off Chile [34], revealed presence and expression of genes encoding for low-affinity cytochrome c oxidases (Km ~200 nmol O2 l-1) as well as high-affinity cytochrome bd and cbb3 oxidases (Km <10 nmol O2 l-1) [38] from the oxycline down to the OMZ core (Fig 2 and S3 Table).

Bottom Line: Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms.In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters.Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

View Article: PubMed Central - PubMed

Affiliation: Biogeochemistry Department, Max Planck Institute for Marine Microbiology, Bremen, Germany.

ABSTRACT
Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.

No MeSH data available.