Photoacclimation of the polar diatom Chaetoceros neogracilis at low temperature

Type Article
Date 2022-09
Language English
Author(s) Lacour ThomasORCID1, 2, 3, Larivière Jade2, 3, Ferland Joannie2, 3, Morin Philippe-Israël2, 3, Grondin Pierre-LucORCID2, 3, Donaher Natalie4, Cockshutt Amanda4, Campbell Douglas A.4, Babin Marcel2, 3
Affiliation(s) 1 : Ifremer, PHYTOX, PHYSALG, Brest, France
2 : Département de Biologie, Takuvik International Research Laboratory (IRL-3376, CNRS, France
3 : ULaval (Canada), Université Laval, Québec, Canada
4 : Department of Chemistry and Biochemistry, Mount Allison University, Sackville, Canada
Source Plos One (1932-6203) (Public Library of Science (PLoS)), 2022-09 , Vol. 17 , N. 9 , P. e0272822 (20p.)
DOI 10.1371/journal.pone.0272822
WOS© Times Cited 1

Polar microalgae face two major challenges: 1- growing at temperatures (-1.7 to 5°C) that limit enzyme kinetics; and 2- surviving and exploiting a wide range of irradiance. The objective of this study is to understand the adaptation of an Arctic diatom to its environment by studying its ability to acclimate to changes in light and temperature. We acclimated the polar diatom Chaetoceros neogracilis to various light levels at two different temperatures and studied its growth and photosynthetic properties using semi-continuous cultures. Rubisco content was high, to compensate for low catalytic rates, but did not change detectably with growth temperature. Contrary to what is observed in temperate species, in C. neogracilis, carbon fixation rate (20 min 14C incorporation) equaled net growth rate (μ) suggesting very low or very rapid (<20 min) re-oxidation of the newly fixed carbon. The comparison of saturation irradiances for electron transport, oxygen net production and carbon fixation revealed alternative electron pathways that could provide energy and reducing power to the cell without consuming organic carbon which is a very limiting product at low temperatures. High protein contents, low re-oxidation of newly fixed carbon and the use of electron pathways alternative to carbon fixation may be important characteristics allowing efficient growth under those extreme environmental conditions.

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S1 Fig. C/N ratio (A) and Cell mean diameter (B) versus growth irradiance at 0 (circles) and 5°C (triangles). Each data point is the mean of 3 cultures measured each day during 3 consecutive .... 212 KB Open access
S2 Fig. Nitrogen per cell (A) and biovolume (B), C per cell (C) and biovolume (D), Chl a per cell (E) and biovolume (F) versus growth irradiance at 0 (circles) and 5°C (triangles). Each data point... 377 KB Open access
S3 Fig. Acclimation of C. neogracilis absorption properties and photochemistry. 287 KB Open access
S4 Fig. Photoacclimation of carbon fixation 155 KB Open access
S5 Fig. Photoacclimation of carbon fixation. 253 KB Open access
S6 Fig. Acclimation of C. neogracilis photochemistry. 284 KB Open access
S7 Fig. Acclimation of C. neogracilis NPQ. 284 KB Open access
S8 Fig. EKNPQ (A) and NPQmax (B) versus (Dt +Dd)/Chl a at 0°C (circles) and 5°C (circles). In A and B a regression line was fitted on the whole dataset (both 0 and 5°C) with the exception of the.... 296 KB Open access
S9 Fig. Acclimation of C. neogracilis O2 net production. 306 KB Open access
S10 Fig. Data points. 114 KB Open access
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Lacour Thomas, Larivière Jade, Ferland Joannie, Morin Philippe-Israël, Grondin Pierre-Luc, Donaher Natalie, Cockshutt Amanda, Campbell Douglas A., Babin Marcel (2022). Photoacclimation of the polar diatom Chaetoceros neogracilis at low temperature. Plos One, 17(9), e0272822 (20p.). Publisher's official version : , Open Access version :