Comparative energetics of carbon storage molecules in green algae

doi:10.1016/j.algal.2018.01.018

Title: Comparative energetics of carbon storage molecules in green algae

Abstract

Several members of the green algae possess the ability to produce lipids and/or high value compounds in significant quantities. While for several of these green algal species induction of increased lipid production has been shown, and cultivation of species for high value molecules occurs at production scale, the molecular mechanisms governing over-accumulation of molecules synthesized from isoprenoid precursors, carotenoids, for example, have received far less attention. Here, we present a calculation of the required ATP equivalencies per carbon atom and reducing power equivalencies as NADH/NADPH (NAD(P)H) per carbon atom for the isoprenoid molecules ..beta..-carotene (C40), astaxanthin (C40), and squalene (C30). We compared energetic requirements of carbohydrates, triacylglycerol, and isoprenoid molecules under a gradient of conditions of cellular stress. Our calculations revealed slightly less ATP and NAD(P)H equivalency per carbon atom between triacylglycerol and the three isoprenoid molecules. Based on our results, we propose that the driving force for differences in accumulation patterns of carotenoids vs. triacylglycerols in algal cells under stress is largely dependent on the presence and regulation of bypass mechanisms at metabolic junction bottlenecks, like pyruvate dehydrogenase (PDH), within particular species. We provide a discussion of several molecular mechanisms that may influence carbon partitioning within different groups ofmore »« less

Authors:

McKie-Krisberg, Zaid M. ^[1]; Laurens, Lieve M. L. ^[2]; Huang, Andy ^[1]; Polle, Jurgen E. W. ^[1]

City Univ. (CUNY), NY (United States)
National Renewable Energy Lab. (NREL), Golden, CO (United States)

Publication Date:: 2018-02-28

Research Org.:: National Renewable Energy Lab. (NREL), Golden, CO (United States)

Sponsoring Org.:: USDOE Office of Energy Efficiency and Renewable Energy (EERE)

OSTI Identifier:: 1427343

Report Number(s):: NREL/JA-5100-71139
Journal ID: ISSN 2211-9264

Grant/Contract Number:: AC36-08GO28308

Resource Type:: Accepted Manuscript

Journal Name:: Algal Research

Additional Journal Information:: Journal Volume: 31; Journal Issue: C; Journal ID: ISSN 2211-9264

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; green algae; energetics; lipid production

Citation Formats


                    McKie-Krisberg, Zaid M., Laurens, Lieve M. L., Huang, Andy, and Polle, Jurgen E. W. Comparative energetics of carbon storage molecules in green algae.  United States: N. p., 2018. 
        Web.  doi:10.1016/j.algal.2018.01.018.

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                    McKie-Krisberg, Zaid M., Laurens, Lieve M. L., Huang, Andy, & Polle, Jurgen E. W. Comparative energetics of carbon storage molecules in green algae.  United States.  doi:10.1016/j.algal.2018.01.018.

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                    McKie-Krisberg, Zaid M., Laurens, Lieve M. L., Huang, Andy, and Polle, Jurgen E. W. Wed .  
        "Comparative energetics of carbon storage molecules in green algae".  United States.  doi:10.1016/j.algal.2018.01.018.  https://www.osti.gov/servlets/purl/1427343.

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@article{osti_1427343,

  title        = {Comparative energetics of carbon storage molecules in green algae},

  author       = {McKie-Krisberg, Zaid M. and Laurens, Lieve M. L. and Huang, Andy and Polle, Jurgen E. W.},

  abstractNote = {Several members of the green algae possess the ability to produce lipids and/or high value compounds in significant quantities. While for several of these green algal species induction of increased lipid production has been shown, and cultivation of species for high value molecules occurs at production scale, the molecular mechanisms governing over-accumulation of molecules synthesized from isoprenoid precursors, carotenoids, for example, have received far less attention. Here, we present a calculation of the required ATP equivalencies per carbon atom and reducing power equivalencies as NADH/NADPH (NAD(P)H) per carbon atom for the isoprenoid molecules ..beta..-carotene (C40), astaxanthin (C40), and squalene (C30). We compared energetic requirements of carbohydrates, triacylglycerol, and isoprenoid molecules under a gradient of conditions of cellular stress. Our calculations revealed slightly less ATP and NAD(P)H equivalency per carbon atom between triacylglycerol and the three isoprenoid molecules. Based on our results, we propose that the driving force for differences in accumulation patterns of carotenoids vs. triacylglycerols in algal cells under stress is largely dependent on the presence and regulation of bypass mechanisms at metabolic junction bottlenecks, like pyruvate dehydrogenase (PDH), within particular species. We provide a discussion of several molecular mechanisms that may influence carbon partitioning within different groups of green algae, including metabolic inhibition through accumulation of specific substrates related to ATP and reducing equivalent production (NAD(P)H) as well as cellular compartmentalization. This work contributes to the ongoing discussion of cellular homeostatic regulation during stress, as well as the potential mechanisms driving long-term carbon storage as it relates to energy and redox states within the algal cell.},

  doi          = {10.1016/j.algal.2018.01.018},

  journal      = {Algal Research},

  number       = C,

  volume       = 31,

  place        = {United States},

  year         = {2018},

  month        = {2}

}

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Journal Article:

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Accepted Manuscript (DOE)

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DOI: 10.1016/j.algal.2018.01.018

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Figures / Tables:

Figure 1: Shown is an image of an orange cell of D. salina. The orange colour indicates that the cell has over-accumulated β-carotene. The cell has two fagella demonstrating that it is still motile under the carotenogenic conditions.

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