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Single cell analyses reveal contrasting life strategies of the two main nitrifiers in the ocean.

ABSTRACT: Nitrification, the oxidation of ammonia via nitrite to nitrate, is a key process in marine nitrogen (N) cycling. Although oceanic ammonia and nitrite oxidation are balanced, ammonia-oxidizing archaea (AOA) vastly outnumber the main nitrite oxidizers, the bacterial Nitrospinae. The ecophysiological reasons for this discrepancy in abundance are unclear. Here, we compare substrate utilization and growth of Nitrospinae to AOA in the Gulf of Mexico. Based on our results, more than half of the Nitrospinae cellular N-demand is met by the organic-N compounds urea and cyanate, while AOA mainly assimilate ammonium. Nitrospinae have, under in situ conditions, around four-times higher biomass yield and five-times higher growth rates than AOA, despite their ten-fold lower abundance. Our combined results indicate that differences in mortality between Nitrospinae and AOA, rather than thermodynamics, biomass yield and cell size, determine the abundances of these main marine nitrifiers. Furthermore, there is no need to invoke yet undiscovered, abundant nitrite oxidizers to explain nitrification rates in the ocean.

SUBMITTER: Kitzinger K

PROVIDER: S-EPMC7005884 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Single cell analyses reveal contrasting life strategies of the two main nitrifiers in the ocean.

Kitzinger Katharina K Marchant Hannah K HK Bristow Laura A LA Herbold Craig W CW Padilla Cory C CC Kidane Abiel T AT Littmann Sten S Daims Holger H Pjevac Petra P Stewart Frank J FJ Wagner Michael M Kuypers Marcel M M MMM

Nature communications 20200207 1

Nitrification, the oxidation of ammonia via nitrite to nitrate, is a key process in marine nitrogen (N) cycling. Although oceanic ammonia and nitrite oxidation are balanced, ammonia-oxidizing archaea (AOA) vastly outnumber the main nitrite oxidizers, the bacterial Nitrospinae. The ecophysiological reasons for this discrepancy in abundance are unclear. Here, we compare substrate utilization and growth of Nitrospinae to AOA in the Gulf of Mexico. Based on our results, more than half of the Nitrosp ...[more]

PMID: 32034151

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Single cell analyses reveal contrasting life strategies of the two main nitrifiers in the ocean.

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Single cell analyses reveal contrasting life strategies of the two main nitrifiers in the ocean.

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