TY - JOUR
T1 - Euglena gracilis growth and cell composition under different temperature, light and trophic conditions
AU - Wang, Yanming
AU - Seppänen-Laakso, Tuulikki
AU - Rischer, Heiko
AU - Wiebe, Marilyn G.
N1 - Funding Information:
This work was supported by TEKES, the Finnish Funding Agency for Technology and Innovation (https://www.tekes.fi/en/tekes/), through the ALGIND (40149/11) project, and by the European Commission (grant no. 311932, project acronym: SeaBiotech, http://spider.science. strath.ac.uk/seabiotech/), and as a personal grant to YW by the Ella and Georg Ehrnrooth Foundation (http://www.ellageorg.fi/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. VTT (with funds from TEKES and the EU FP7) provided support in the form of salaries for authors [YW, TS-L, HR, MGW], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section. We thank Jaana Rikkinen for her work of strain maintenance.
Publisher Copyright:
© 2018 Wang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Copyright:
Copyright 2018 Elsevier B.V., All rights reserved.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - Background Euglena gracilis, a photosynthetic protist, produces protein, unsaturated fatty acids, wax esters, and a unique β-1,3-glucan called paramylon, along with other valuable compounds. The cell composition of E. gracilis was investigated in this study to understand how light and organic carbon (photo-, mixo- and heterotrophic conditions) affected growth and cell composition (especially lipids). Comparisons were primarily carried out in cultures grown at 23 C, but the effect of growth at higher temperatures (27 or 30 C) was also considered. Cell growth Specific growth rates were slightly lower when E. gracilis was grown on glucose in either heterotrophic or mixotrophic conditions than when grown photoautotrophically, although the duration of exponential growth was longer. Temperature determined the rate of exponential growth in all cultures, but not the linear growth rate during light-limited growth in phototrophic conditions. Temperature had less effect on cell composition. Cell composition Although E. gracilis was not expected to store large amounts of paramylon when grown phototrophically, we observed that phototrophic cells could contain up to 50% paramylon. These cells contained up to 33% protein and less than 20% lipophilic compounds, as expected. The biomass contained about 8% fatty acids (measured as fatty acid methyl esters), most of which were unsaturated. The fatty acid content of cells grown in mixotrophic conditions was similar to that observed in phototrophic cells, but was lower in cells grown heterotrophically. Heterotrophic cells contained less unsaturated fatty acids than phototrophic or mixotrophic cells. α-Linolenic acid was present at 5 to 18 mg g-1 dry biomass in cells grown in the presence of light, but at < 0.5 mg g-1 biomass in cells grown in the dark. Eicosapentaenoic and docosahexaenoic acids were detected at 1 to 5 mg g-1 biomass. Light was also important for the production of vitamin E and phytol.
AB - Background Euglena gracilis, a photosynthetic protist, produces protein, unsaturated fatty acids, wax esters, and a unique β-1,3-glucan called paramylon, along with other valuable compounds. The cell composition of E. gracilis was investigated in this study to understand how light and organic carbon (photo-, mixo- and heterotrophic conditions) affected growth and cell composition (especially lipids). Comparisons were primarily carried out in cultures grown at 23 C, but the effect of growth at higher temperatures (27 or 30 C) was also considered. Cell growth Specific growth rates were slightly lower when E. gracilis was grown on glucose in either heterotrophic or mixotrophic conditions than when grown photoautotrophically, although the duration of exponential growth was longer. Temperature determined the rate of exponential growth in all cultures, but not the linear growth rate during light-limited growth in phototrophic conditions. Temperature had less effect on cell composition. Cell composition Although E. gracilis was not expected to store large amounts of paramylon when grown phototrophically, we observed that phototrophic cells could contain up to 50% paramylon. These cells contained up to 33% protein and less than 20% lipophilic compounds, as expected. The biomass contained about 8% fatty acids (measured as fatty acid methyl esters), most of which were unsaturated. The fatty acid content of cells grown in mixotrophic conditions was similar to that observed in phototrophic cells, but was lower in cells grown heterotrophically. Heterotrophic cells contained less unsaturated fatty acids than phototrophic or mixotrophic cells. α-Linolenic acid was present at 5 to 18 mg g-1 dry biomass in cells grown in the presence of light, but at < 0.5 mg g-1 biomass in cells grown in the dark. Eicosapentaenoic and docosahexaenoic acids were detected at 1 to 5 mg g-1 biomass. Light was also important for the production of vitamin E and phytol.
UR - http://www.scopus.com/inward/record.url?scp=85045417742&partnerID=8YFLogxK
U2 - 10.1371/journal.pone.0195329
DO - 10.1371/journal.pone.0195329
M3 - Article
AN - SCOPUS:85045417742
SN - 1932-6203
VL - 13
JO - PLoS ONE
JF - PLoS ONE
IS - 4
M1 - e0195329
ER -