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

• Published in: Nature Communications
• Main Authors: Ya-Wei Luo, 罗亚威, Dalin Shi, 史大林, Sven A. Kranz, Brian M. Hopkinson, Haizheng Hong, 洪海征, Rong Shen, 沈容, Futing Zhang, 张福婷
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Nature Publishing AG 2019
• Subjects: Marine biology; Microbial ecology; Sven; Ocean acidification
• Online Access: https://doi.org/10.1038/s41467-019-09554-7; https://dspace.xmu.edu.cn/handle/2288/171208

工业革命以来，海洋吸收了约三分之一人为排放的CO2，以迄今3亿年来最快的速度酸化（CO2升高、pH下降），这势必影响海洋生态系统的关键过程和功能。研究团队创新性地从区分海洋酸化过程中CO2上升和pH下降的双重效应入手，揭示了海水CO2升高的正效应小于pH下降的负效应，故酸化的净效应为抑制束毛藻的固氮作用。这是因为酸化引起束毛藻胞质 pH下降，从而降低固氮酶效率、干扰胞内pH稳态、影响细胞产能。在上述研究工作的基础上，进一步系统地测定了固氮和光合系统蛋白的表达量及其含铁量，建立了一个束毛藻的“资源最优化分配”细胞模型。实现了实验数据和数值模型的紧密结合：实验数据是构筑模型的坚实基础，并提高了模型的预测水平；通过模型模拟，加深了对实验发现的认知，并对实验结论进行了时空拓展。 罗亚威博士和史大林博士为论文的共同第一作者和共同通讯作者，史大林课题组的洪海征教授、研究助理沈容和博士生张福婷为共同作者。论文的共同作者还包括美国佛罗里达州立大学助理教授Sven Kranz博士和乔治亚大学副教授Brian Hopkinson博士。 【Abstract】The response of the prominent marine dinitrogen (N2)-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 N2 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 (CO2)-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 CO2 emissions continue to rise, OA could reduce global N2 fixation potential of Trichodesmium by 27% in this century, with the largest decrease in iron-limiting regions. This work was funded by the National Key R&D Program of China (2016YFA0601404 and 2016YFA0601203), NSFC (41476093, 41721005, 41890802, 31861143022 and 41376116), and the MEL internal research fund (MELRI1502).本项研究得到了国家重点研发计划（2016YFA0601404 和2016YFA0601203）以及国家自然科学基金系列项目（41476093, 41721005, 41890802, 31861143022 和41376116）的资助。