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Quantifying nitrogen fixation by heterotrophic bacteria in sinking marine particles
Name
s41467-021-23875-6.pdf
Description
Published version
Size
2.22 MB
Format
Adobe PDF
Checksum (MD5)
a1b4375b5bcb462db347390776fc2c93
Author(s)
Chakraborty, Subhendu
Andersen, Ken H
Visser, André W
Inomura, Keisuke
Follows, Michael J
Riemann, Lasse
Date Issued
December 2021
Journal
Nature Communications
Publisher
Springer Science and Business Media LLC
Version
Final published version
Abstract
AbstractNitrogen ($${{\rm{N}}}_{2}$$
N 2 ) fixation by heterotrophic bacteria associated with sinking particles contributes to marine N cycling, but a mechanistic understanding of its regulation and significance are not available. Here we develop a mathematical model for unicellular heterotrophic bacteria growing on sinking marine particles. These bacteria can fix $${{\rm{N}}}_{2}$$ N 2 under suitable environmental conditions. We find that the interactive effects of polysaccharide and polypeptide concentrations, sinking speed of particles, and surrounding $${{\rm{O}}}_{2}$$ O 2 and $${{{\rm{NO}}}_{3}}^{-}$$ NO 3 − concentrations determine the $${{\rm{N}}}_{2}$$ N 2 fixation rate inside particles. $${{\rm{N}}}_{2}$$ N 2 fixation inside sinking particles is mainly fueled by $${{{\rm{SO}}}_{4}}^{2-}$$ SO 4 2 − respiration rather than $${{{\rm{NO}}}_{3}}^{-}$$ NO 3 − respiration. Our model suggests that anaerobic processes, including heterotrophic $${{\rm{N}}}_{2}$$ N 2 fixation, can take place in anoxic microenvironments inside sinking particles even in fully oxygenated marine waters. The modelled $${{\rm{N}}}_{2}$$ N 2 fixation rates are similar to bulk rates measured in the aphotic ocean, and our study consequently suggests that particle-associated heterotrophic $${{\rm{N}}}_{2}$$ N 2 fixation contributes significantly to oceanic $${{\rm{N}}}_{2}$$ N 2 fixation.
N 2 ) fixation by heterotrophic bacteria associated with sinking particles contributes to marine N cycling, but a mechanistic understanding of its regulation and significance are not available. Here we develop a mathematical model for unicellular heterotrophic bacteria growing on sinking marine particles. These bacteria can fix $${{\rm{N}}}_{2}$$ N 2 under suitable environmental conditions. We find that the interactive effects of polysaccharide and polypeptide concentrations, sinking speed of particles, and surrounding $${{\rm{O}}}_{2}$$ O 2 and $${{{\rm{NO}}}_{3}}^{-}$$ NO 3 − concentrations determine the $${{\rm{N}}}_{2}$$ N 2 fixation rate inside particles. $${{\rm{N}}}_{2}$$ N 2 fixation inside sinking particles is mainly fueled by $${{{\rm{SO}}}_{4}}^{2-}$$ SO 4 2 − respiration rather than $${{{\rm{NO}}}_{3}}^{-}$$ NO 3 − respiration. Our model suggests that anaerobic processes, including heterotrophic $${{\rm{N}}}_{2}$$ N 2 fixation, can take place in anoxic microenvironments inside sinking particles even in fully oxygenated marine waters. The modelled $${{\rm{N}}}_{2}$$ N 2 fixation rates are similar to bulk rates measured in the aphotic ocean, and our study consequently suggests that particle-associated heterotrophic $${{\rm{N}}}_{2}$$ N 2 fixation contributes significantly to oceanic $${{\rm{N}}}_{2}$$ N 2 fixation.
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DOI of Published Version
10.1038/s41467-021-23875-6
