Reduced nitrogenase efficiency dominates response of the globally important nitrogen fixer Trichodesmium to ocean acidification

• Published in: Nature communications Vol. 10; no. 1; p. 1521
• Main Authors: Luo, Ya-Wei, Shi, Dalin, Kranz, Sven A., Hopkinson, Brian M., Hong, Haizheng, Shen, Rong, Zhang, Futing
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.04.2019; Nature Publishing Group; Nature Portfolio
• Subjects: 704/158/855; 704/829/826; 82/80; Acidification; Anthropogenic factors; Biogeochemical cycles; Carbon dioxide; Carbon Dioxide - metabolism; Carbon Dioxide - pharmacology; Carbon dioxide emissions; Computer Simulation; Cyanobacteria; Data processing; Energy demand; Energy Metabolism - drug effects; Ferredoxins - metabolism; Fixation; Growth rate; Human influences; Humanities and Social Sciences; Hydrogen-Ion Concentration; Iron; Iron - metabolism; Models, Theoretical; multidisciplinary; Nitrogen - metabolism; Nitrogen Fixation - physiology; Nitrogenase; Nitrogenase - metabolism; Nitrogenation; Ocean acidification; Oceans and Seas; Science; Science (multidisciplinary); Seawater - chemistry; Seawater - microbiology; Trichodesmium; Trichodesmium - drug effects; Trichodesmium - enzymology; Trichodesmium - growth & development; Trichodesmium - metabolism
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-09554-7

The response of the prominent marine dinitrogen (N 2 )-fixing cyanobacteria Trichodesmium to ocean acidification (OA) is critical to understanding future oceanic biogeochemical cycles. Recent studies have reported conflicting findings on the effect of OA on growth and N 2 fixation of Trichodesmium . Here, we quantitatively analyzed experimental data on how Trichodesmium reallocated intracellular iron and energy among key cellular processes in response to OA, and integrated the findings to construct an optimality-based cellular model. The model results indicate that Trichodesmium growth rate decreases under OA primarily due to reduced nitrogenase efficiency. The downregulation of the carbon dioxide (CO 2 )-concentrating mechanism under OA has little impact on Trichodesmium , and the energy demand of anti-stress responses to OA has a moderate negative effect. We predict that if anthropogenic CO 2 emissions continue to rise, OA could reduce global N 2 fixation potential of Trichodesmium by 27% in this century, with the largest decrease in iron-limiting regions. Findings regarding the impacts of ocean acidification (OA) on the growth and N 2 fixation of Trichodesmium are conflicted. Here, the authors find that Trichodesmium growth rates decrease under OA primarily due to reduced nitrogenase efficiency and OA under RCP 8.5 could reduce the N 2 fixation potential of Trichodesmium by 27%.