AME - Vol. 70 No. 3 - Feature article

Nitrogen removal genes (yellow curve) peaked at the top of the OMZ (red curve shows O2 concentration). The nirS assemblage differed between oxic (upper array) and OMZ (lower array) waters and between oceanic regions. Image: Bess Ward

Jayakumar A, Peng X, Ward BB

 

Community composition of bacteria involved in fixed nitrogen loss in the water column of two major oxygen minimum zones in the ocean

 

The Eastern Tropical South Pacific and the Arabian Sea are 2 of the 3 permanent oxygen minimum zones (OMZs), where the majority of oceanic fixed nitrogen removal takes place. Community composition and abundance of microbes involved in nitrogen cycling in the water column above and within the oxygen depleted depths of these OMZs were investigated by targeting key genes in N transformation processes. The results of our work show that nirS gene-containing denitrifying bacteria dominate low oxygen depths, where anammox bacteria also exhibit maximum abundance. Hybridization with a functional gene microarray targeting the nirS gene showed that the communities were clearly distinct between the 2 geographically separated regions and also between the surface oxic waters and the oxygen depleted layer.

 

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