Nitrifiers drive successions of particulate organic matter and microbial community composition in a starved macrocosm

https://doi.org/10.1016/j.envint.2021.106776Get rights and content
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Highlights

  • Particulate nitrogenous compounds increased in the later stage of the incubation.

  • Nitrifiers abundance was positively coupled to particulate nitrogenous compounds.

  • Compounds released by nitrifiers triggered degradation of refractory organic matter.

Abstract

Organic carbon produced by nitrifiers plays an important role in maintaining the microbial metabolism in the aphotic ocean layer with carbon and energy scarcity. However, the contribution of nitrifiers to organic carbon processing remains unclear. To explore how nitrification impacts the material cycle in the starved ecosystem, we set up an ultra-large volume, long-term incubation experiment. Seawater collected from the Halifax coastal ocean was pumped into the Aquatron Tower Tank located at Dalhousie University, Canada, and was incubated under dark conditions for 73 days. The results indicated that the relative abundance of nitrifiers increased and nitrification was strengthened in the dark system where energy and organic carbon were scarce. The importance of nitrogenous compounds in particulate materials increased over the course of the incubation. Correlation analysis showed that the relative abundances of nitrifiers and particulate organic compounds containing nitrogen were significantly and positively correlated. Furthermore, network analysis suggested that metabolic processes related to nitrogenous and aromatic compounds are most important to particle associated bacteria. This study suggests that the nitrifiers could produce a series of organic compounds that result in the alteration of organic matter composition by promoting the degradation of recalcitrant aromatic compounds, which has important implications for organic matter processing in the starved dark ecosystem.

Keywords

Nitrifiers
Nitrification
Particulate organic matter
Nitrogenous compounds
Aromatic compounds
Starved dark ecosystem

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