Electron & Biomass Dynamics of Cyanothece Under Interacting Nitrogen & Carbon Limitations
Rabouille, Sophie; Campbell, Douglas A.; Masuda, Takako; Zavřel, Tomáš; Bernat, Gabor; Polerecky, Lubos; Halsey, Kimberly; Eichner, Meri; Kotabová, Eva; Stephan, Susanne; Lukeš, Martin; Claquin, Pascal; Bonomi-Barufi, José; Lombardi, Ana Teresa; Červený, Jan; Suggett, David J.; Giordano, Mario; Kromkamp, Jacco C.; Prášil, Ondřej
(2021) Frontiers in Microbiology, volume 12, pp. 1 - 21
(Article)
Abstract
Marine diazotrophs are a diverse group with key roles in biogeochemical fluxes linked to primary productivity. The unicellular, diazotrophic cyanobacterium Cyanothece is widely found in coastal, subtropical oceans. We analyze the consequences of diazotrophy on growth efficiency, compared to NO3–-supported growth in Cyanothece, to understand how cells cope with N2-fixation
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when they also have to face carbon limitation, which may transiently affect populations in coastal environments or during blooms of phytoplankton communities. When grown in obligate diazotrophy, cells face the double burden of a more ATP-demanding N-acquisition mode and additional metabolic losses imposed by the transient storage of reducing potential as carbohydrate, compared to a hypothetical N2 assimilation directly driven by photosynthetic electron transport. Further, this energetic burden imposed by N2-fixation could not be alleviated, despite the high irradiance level within the cultures, because photosynthesis was limited by the availability of dissolved inorganic carbon (DIC), and possibly by a constrained capacity for carbon storage. DIC limitation exacerbates the costs on growth imposed by nitrogen fixation. Therefore, the competitive efficiency of diazotrophs could be hindered in areas with insufficient renewal of dissolved gases and/or with intense phytoplankton biomass that both decrease available light energy and draw the DIC level down.
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Keywords: Crocosphaera subtropica, Cyanothece, carbon limitation, light limitation, nitrogen fixation, photosynthesis, Microbiology, Microbiology (medical)
ISSN: 1664-302X
Publisher: Frontiers Media S.A.
Note: Funding Information: This work results from the Group for Aquatic Photosynthesis (GAP) workshop held in T?ebo?, Czech Republic, in August 2017 and subsequent discussions. We are thankful to Erika Weiz-Bersch for her help with DIC measurements. We are also very thankful to the reviewers who evaluated this work. Their thorough reading and extremely constructive comments was very inspiring to produce a more didactic, final version of this manuscript. Funding. SR acknowledges support from the LEFE-INSU funding program. DC was supported by Mobility project: CZ.02.2.69/0.0/0.0/16_027/0007990, international mobility of researchers of the Institute of Microbiology of the CAS. TM and OP were supported by the Czech science foundation (GACR 20-17627S). The work of GB was partly supported by the National Research, Development and Innovation Office of Hungary, NKFIH, grant No. K 128950. J? and TZ were supported by the Ministry of Education, Youth and Sports of the Czech Republic (OP RDE grant number CZ.02.1.01/0.0/0.0/16?026/0008413 ?Strategic Partnership for Environmental Technologies and Energy Production?) and by the Czech Science Foundation (GA CR, grant number 19-00973S). SS was supported by ILES (Illuminating Lake Ecosystem), a project funded through the Leibniz Competition (SAW-2015-IGB-1). AL was supported by FAPESP Grant No. 2017/12450-1. JB-B was supported by the National Council for Scientific and Technological Development (CNPq, proc. n.304122/2017-3). Funding Information: SR acknowledges support from the LEFE-INSU funding program. DC was supported by Mobility project: CZ.02.2.69/0.0/0.0/16_027/0007990, international mobility of researchers of the Institute of Microbiology of the CAS. TM and OP were supported by the Czech science foundation (GACR 20-17627S). The work of GB was partly supported by the National Research, Development and Innovation Office of Hungary, NKFIH, grant No. K 128950. JCˇ and TZ were supported by the Ministry of Education, Youth and Sports of the Czech Republic (OP RDE grant number CZ.02.1.01/0.0/0.0/16–026/0008413 Publisher Copyright: © Copyright © 2021 Rabouille, Campbell, Masuda, Zavřel, Bernát, Polerecky, Halsey, Eichner, Kotabová, Stephan, Lukeš, Claquin, Bonomi-Barufi, Lombardi, Červený, Suggett, Giordano, Kromkamp and Prášil.
(Peer reviewed)