The complex effects of ocean acidification on the prominent N2-fixing cyanobacterium Trichodesmium
The complex effects of ocean acidification on the prominent N2-fixing cyanobacterium Trichodesmium
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海洋酸化对重要的固氮蓝藻Trichodesmium的复杂影响
DOI：
10.1126/science.aal2981
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发表时间：
2017-05-05
期刊：
影响因子：
56.9
通讯作者：
Shi, Dalin
中科院分区：
文献类型：
--
作者：
Hong, Haizheng;Shen, Rong;Shi, Dalin
尽管二氧化碳浓度升高具有施肥作用，但未来海洋的酸性更强，其生产力可能会降低。协调 pH 值和未来生产力 海水 pH 值降低和二氧化碳增加对海洋浮游植物生产力的不同影响尚未得到解决。洪等人。发现之前的实验没有考虑可变的金属浓度或氨污染。在控制这些变量后，实验、蛋白质表达分析和现场数据表明，低 pH 值，加上公海中铁含量低，会抑制固氮作用，而二氧化碳浓度升高则会起到施肥作用。总体而言，pH 值降低的有害影响胜过二氧化碳增加的有益影响。因此，在未来，海洋酸性更强时，浮游植物的生产力可能会受到抑制。科学，本期第 14 页。 527 人为二氧化碳 (CO2) 造成的海水酸化预计会影响固定氮 (N2) 的浮游植物的生长，而浮游植物在热带和亚热带海洋的初级生产中占很大一部分。我们发现，尽管高二氧化碳具有有益作用，但在酸化条件下，普遍存在的蓝藻Trichodesmium 的生长和固氮能力都会下降。尽管固氮酶浓度升高，但酸化导致胞质 pH 值降低并降低 N2 固定率。低胞质 pH 值需要增加穿过类囊体膜的质子泵送和增加三磷酸腺苷的产量。这些要求在现场或实验限铁条件下无法得到满足，从而大大放大了酸化的负面影响。
A future, more acidic ocean could be less productive, despite the fertilizing effects of elevated CO2. Reconciling pH and future productivity The differential effects of reduced seawater pH and increased carbon dioxide on marine phytoplankton productivity have not been resolved. Hong et al. found that previous experimentation did not account for variable metal concentrations or for ammonia contamination. After controlling for these variables, experimentation, protein expression analysis, and field data showed that low pH, coupled with the low ambient iron availability in the open ocean, inhibits nitrogen fixation, whereas elevated CO2 is fertilizing. Overall, the deleterious effects of decreased pH trump the beneficial effects of increased CO2. Thus, it seems that in a future, more acidic ocean, phytoplankton productivity is likely to be suppressed. Science, this issue p. 527 Acidification of seawater caused by anthropogenic carbon dioxide (CO2) is anticipated to influence the growth of dinitrogen (N2)–fixing phytoplankton, which contribute a large fraction of primary production in the tropical and subtropical ocean. We found that growth and N2-fixation of the ubiquitous cyanobacterium Trichodesmium decreased under acidified conditions, notwithstanding a beneficial effect of high CO2. Acidification resulted in low cytosolic pH and reduced N2-fixation rates despite elevated nitrogenase concentrations. Low cytosolic pH required increased proton pumping across the thylakoid membrane and elevated adenosine triphosphate production. These requirements were not satisfied under field or experimental iron-limiting conditions, which greatly amplified the negative effect of acidification.