Quantifying nutrient throughput and DOM production by algae in continuous culture

A. W. Omta, D. Talmy, K. Inomura, A. J. Irwin, Z. V. Finkel, D. Sher, J. D. Liefer, M. J. Follows

Research output: Contribution to journalArticlepeer-review


Freshwater and marine algae can balance nutrient demand and availability by regulating uptake, accumulation and exudation. To obtain insight into these processes under nitrogen (N) and phosphorus (P) limitation, we reanalyze published data from continuous cultures of the chlorophyte Selenastrum minutum. Based on mass budgets, we argue that much of the non‐limiting N and P had passed through the organisms and was present as dissolved organic phosphorus or nitrogen (DOP or DON). We construct a model that describes the production of biomass and dissolved organic matter (DOM) as a function of the growth rate. A fit of this model against the chemostat data suggests a high turnover of the non‐limiting N and P: at the highest growth rates, N and P atoms spent on average only about 3 h inside an organism, before they were exuded as DON and DOP, respectively. This DOM exudation can explain the observed trends in the algal stoichiometric ratios as a function of the dilution rate. We discuss independent evidence from isotope experiments for this apparently wasteful behavior and we suggest experiments to quantify and characterize DON and DOP exudation further.

Original languageEnglish
Article number110214
JournalJournal of Theoretical Biology
StatePublished - 7 Jun 2020

Bibliographical note

Funding Information:
The authors would like to thank Dave Turpin, Ivor Elrifi, Harold Weger, and two anonymous reviewers for helpful comments and discussions. This work was supported by the Simons Collaboration on Computational Biogeochemical Modeling of Marine Ecosystems/ CBIOMES (Grant ID: 549931 , MJF). Furthermore, the authors are grateful for support from the Gordon & Betty Moore Foundation [Grant number GBMF #3778 ], the National Science Foundation [Grant numbers NSF‐OCE‐1315201 , NSF‐OCE‐1536521 to DT and MJF], the Simons Foundation [Simons Postdoctoral Fellowship in Marine Microbial Ecology, Award 544338, KI], the Natural Sciences and Engineering Research Council of Canada to AJI and ZVF, and the United States‐Israel Binational Science Foundation [Grant number 2010183 to DS and MJF].

Publisher Copyright:
© 2020


  • Algal stoichiometry
  • DOM production
  • Plankton model
  • Plankton physiology

ASJC Scopus subject areas

  • Statistics and Probability
  • Modeling and Simulation
  • Biochemistry, Genetics and Molecular Biology (all)
  • Immunology and Microbiology (all)
  • Agricultural and Biological Sciences (all)
  • Applied Mathematics


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