Limits...
Diversity and spatial distribution of hydrazine oxidoreductase (hzo) gene in the oxygen minimum zone off Costa Rica.

Kong L, Jing H, Kataoka T, Buchwald C, Liu H - PLoS ONE (2013)

Bottom Line: In this study, anammox bacterial communities in the OMZ off Costa Rica (CRD-OMZ) were analyzed based on both hydrazine oxidoreductase (hzo) genes and their transcripts assigned to cluster 1 and 2.Gene quantification results showed that hzo gene abundances peaked in the upper OMZs, associated with the peaks of nitrite concentration.A novel hzo cluster 2x clade was identified by the phylogenetic analysis and these novel sequences were abundant and widely distributed in this environment.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.

ABSTRACT
Anaerobic ammonia oxidation (anammox) as an important nitrogen loss pathway has been reported in marine oxygen minimum zones (OMZs), but the community composition and spatial distribution of anammox bacteria in the eastern tropical North Pacific (ETNP) OMZ are poorly determined. In this study, anammox bacterial communities in the OMZ off Costa Rica (CRD-OMZ) were analyzed based on both hydrazine oxidoreductase (hzo) genes and their transcripts assigned to cluster 1 and 2. The anammox communities revealed by hzo genes and proteins in CRD-OMZ showed a low diversity. Gene quantification results showed that hzo gene abundances peaked in the upper OMZs, associated with the peaks of nitrite concentration. Nitrite and oxygen concentrations may therefore colimit the distribution of anammox bacteria in this area. Furthermore, transcriptional activity of anammox bacteria was confirmed by obtaining abundant hzo mRNA transcripts through qRT-PCR. A novel hzo cluster 2x clade was identified by the phylogenetic analysis and these novel sequences were abundant and widely distributed in this environment. Our study demonstrated that both cluster 1 and 2 anammox bacteria play an active role in the CRD-OMZ, and the cluster 1 abundance and transcriptional activity were higher than cluster 2 in both free-living and particle-attached fractions at both gene and transcriptional levels.

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Related in: MedlinePlus

Hydrographic conditions of the sampling stations.Shadow layers indicate the core of the oxygen minimum zones (OMZs) characterized by dissolved oxygen concentration lower than 1.0 μM.
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pone-0078275-g002: Hydrographic conditions of the sampling stations.Shadow layers indicate the core of the oxygen minimum zones (OMZs) characterized by dissolved oxygen concentration lower than 1.0 μM.

Mentions: Similar hydrographic characteristics of the water columns were shown at the three stations (Figure 2). Salinity increased and temperature decreased sharply at the depth of 30-40 m, corresponding to the upwelling front, where a stable thermocline was generated. Dissolved oxygen concentration decreased from the surface until a secondary peak appeared at around 200 m depth, and then decreased again to a very low value, where the OMZs of around 300 m thick were formed below 300 m. A subsurface peak of ammonium and nitrite concentrations in the euphotic zone was observed and nitrite concentration reached its maximum of 0.98-1.50 μM within the OMZ. Below the nitrite peak, ammonium began to accumulate with nitrite concentration dropped to the background value (Figure 3). Based on the profiles of dissolved oxygen and nutrients, water layers outside the OMZ (above and below the OMZ) and the core OMZ layer (dissolved oxygen ≤ 1.0 μM) could be clearly defined. Inside the core OMZ layer, the region between the upper OMZ boundary (oxic-suboxic boundary) and the layer of the nitrite peak was defined as the upper OMZ; the region between the layer of nitrite peak and lower OMZ boundary was defined as the lower OMZ.


Diversity and spatial distribution of hydrazine oxidoreductase (hzo) gene in the oxygen minimum zone off Costa Rica.

Kong L, Jing H, Kataoka T, Buchwald C, Liu H - PLoS ONE (2013)

Hydrographic conditions of the sampling stations.Shadow layers indicate the core of the oxygen minimum zones (OMZs) characterized by dissolved oxygen concentration lower than 1.0 μM.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814345&req=5

pone-0078275-g002: Hydrographic conditions of the sampling stations.Shadow layers indicate the core of the oxygen minimum zones (OMZs) characterized by dissolved oxygen concentration lower than 1.0 μM.
Mentions: Similar hydrographic characteristics of the water columns were shown at the three stations (Figure 2). Salinity increased and temperature decreased sharply at the depth of 30-40 m, corresponding to the upwelling front, where a stable thermocline was generated. Dissolved oxygen concentration decreased from the surface until a secondary peak appeared at around 200 m depth, and then decreased again to a very low value, where the OMZs of around 300 m thick were formed below 300 m. A subsurface peak of ammonium and nitrite concentrations in the euphotic zone was observed and nitrite concentration reached its maximum of 0.98-1.50 μM within the OMZ. Below the nitrite peak, ammonium began to accumulate with nitrite concentration dropped to the background value (Figure 3). Based on the profiles of dissolved oxygen and nutrients, water layers outside the OMZ (above and below the OMZ) and the core OMZ layer (dissolved oxygen ≤ 1.0 μM) could be clearly defined. Inside the core OMZ layer, the region between the upper OMZ boundary (oxic-suboxic boundary) and the layer of the nitrite peak was defined as the upper OMZ; the region between the layer of nitrite peak and lower OMZ boundary was defined as the lower OMZ.

Bottom Line: In this study, anammox bacterial communities in the OMZ off Costa Rica (CRD-OMZ) were analyzed based on both hydrazine oxidoreductase (hzo) genes and their transcripts assigned to cluster 1 and 2.Gene quantification results showed that hzo gene abundances peaked in the upper OMZs, associated with the peaks of nitrite concentration.A novel hzo cluster 2x clade was identified by the phylogenetic analysis and these novel sequences were abundant and widely distributed in this environment.

View Article: PubMed Central - PubMed

Affiliation: Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.

ABSTRACT
Anaerobic ammonia oxidation (anammox) as an important nitrogen loss pathway has been reported in marine oxygen minimum zones (OMZs), but the community composition and spatial distribution of anammox bacteria in the eastern tropical North Pacific (ETNP) OMZ are poorly determined. In this study, anammox bacterial communities in the OMZ off Costa Rica (CRD-OMZ) were analyzed based on both hydrazine oxidoreductase (hzo) genes and their transcripts assigned to cluster 1 and 2. The anammox communities revealed by hzo genes and proteins in CRD-OMZ showed a low diversity. Gene quantification results showed that hzo gene abundances peaked in the upper OMZs, associated with the peaks of nitrite concentration. Nitrite and oxygen concentrations may therefore colimit the distribution of anammox bacteria in this area. Furthermore, transcriptional activity of anammox bacteria was confirmed by obtaining abundant hzo mRNA transcripts through qRT-PCR. A novel hzo cluster 2x clade was identified by the phylogenetic analysis and these novel sequences were abundant and widely distributed in this environment. Our study demonstrated that both cluster 1 and 2 anammox bacteria play an active role in the CRD-OMZ, and the cluster 1 abundance and transcriptional activity were higher than cluster 2 in both free-living and particle-attached fractions at both gene and transcriptional levels.

Show MeSH
Related in: MedlinePlus