High diversity of ammonia-oxidizing archaea in permanent and seasonal oxygen-deficient waters of the eastern South Pacific

The community structure of putative aerobic ammonia-oxidizing archaea (AOA) was explored in two oxygen-deficient ecosystems of the eastern South Pacific: the oxygen minimum zone off Peru and northern Chile (11°S-20°S), where permanent suboxic and low-ammonium conditions are found at intermediate dep...

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Bibliographic Details
Published in:Environmental microbiology 2010-09, Vol.12 (9), p.2450-2465
Main Authors: Molina, Verónica, Belmar, Lucy, Ulloa, Osvaldo
Format: Article
Language:English
Subjects:
Ammonia - metabolism
Archaea
Archaea - classification
Archaea - genetics
Archaea - metabolism
Betaproteobacteria - genetics
Chile
DNA, Archaeal - genetics
Genes, Archaeal
Genotype
Nitrogen - analysis
Oxidoreductases - genetics
Oxygen - analysis
Pacific Ocean
Peru
Phylogeny
Proteobacteria
Seawater - analysis
Seawater - microbiology
Water Microbiology
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Summary:The community structure of putative aerobic ammonia-oxidizing archaea (AOA) was explored in two oxygen-deficient ecosystems of the eastern South Pacific: the oxygen minimum zone off Peru and northern Chile (11°S-20°S), where permanent suboxic and low-ammonium conditions are found at intermediate depths, and the continental shelf off central Chile (36°S), where seasonal oxygen-deficient and relatively high-ammonium conditions develop in the water column, particularly during the upwelling season. The AOA community composition based on the ammonia monooxygenase subunit A (amoA) genes changed according to the oxygen concentration in the water column and the ecosystem studied, showing a higher diversity in the seasonal low-oxygen waters. The majority of the archaeal amoA genotypes was affiliated to the uncultured clusters A (64%) and B (35%), with Cluster A AOA being mainly associated with higher oxygen and ammonium concentrations and Cluster B AOA with permanent oxygen- and ammonium-poor waters. Q-PCR assays revealed that AOA are an abundant community (up to 10⁵amoA copies ml⁻¹), while bacterial amoA genes from β proteobacteria were undetected. Our results thus suggest that a diverse uncultured AOA community, for which, therefore, we do not have any physiological information, to date, is an important component of the nitrifying community in oxygen-deficient marine ecosystems, and particularly in rich coastal upwelling ones.
ISSN:1462-2912
1462-2920
DOI:10.1111/j.1462-2920.2010.02218.x