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Original Research ARTICLE

Front. Plant Sci. | doi: 10.3389/fpls.2017.00847

Amino acids are an ineffective fertilizer for Dunaliella spp. growth

  • 1Department of Plant and Microbial Biology, North Carolina State University, United States
  • 2Department of Plant Pathology, Physiology, & Weed Science, Virginia Polytechnic Institute and State University, United States
  • 3Department of Biomedical Engineering, University of North Carolina School of Medicine, United States

Autotrophic microalgae are a promising bioproducts platform. However, the fundamental requirements these organisms have for nitrogen fertilizer severely limit the impact and scale of their cultivation. As an alternative to inorganic fertilizers, we investigated the possibility of using amino acids from deconstructed biomass as a nitrogen source in the genus Dunaliella. We found that only four amino acids (glutamine, histidine, cysteine, and tryptophan) rescue Dunaliella spp. growth in nitrogen depleted media, and that supplementation of these amino acids altered the metabolic profile of Dunaliella spp. cells. Our investigations revealed that histidine is transported across the cell membrane, and that glutamine and cysteine are not transported. Rather, glutamine, cysteine, and tryptophan are degraded in solution by a set of oxidative chemical reactions, releasing ammonium that in turn supports growth. Utilization of biomass-derived amino acids is therefore not a suitable option unless additional amino acid nitrogen uptake is enabled through genetic modifications of these algae.

Keywords: Nitrogen recycling, Lipids, Biofuels, Amino Acids, dunaliella, sustainability

Received: 02 Mar 2017; Accepted: 08 May 2017.

Edited by:

Julian Eaton-Rye, University of Otago, New Zealand

Reviewed by:

Benoit Guieysse, Massey University, New Zealand
Mike Packer, Cawthron Institute, New Zealand  

Copyright: © 2017 Murphree, Dums, Jain, Zhao, Young, Khoshnoodi, Tikunov, Macdonald, Pilot and Sederoff. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: PhD. Heike Sederoff, North Carolina State University, Department of Plant and Microbial Biology, Raleigh, 27695-7649, NC, United States, hwsedero@ncsu.edu