Molecular mechanisms underlying iron and phosphorus co-limitation responses in the nitrogen-fixing cyanobacterium Crocosphaera
Molecular mechanisms underlying iron and phosphorus co-limitation responses in the nitrogen-fixing cyanobacterium Crocosphaera
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DOI：
10.1038/s41396-022-01307-7
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发表时间：
2022-08
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影响因子：
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通讯作者：
Nina Yang;Yu-An Lin;C. Merkel;Michelle A. DeMers;Ping-Ping Qu-Ping;E. Webb;Feixue Fu;D. Hutchins
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文献类型：
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作者：
Nina Yang;Yu-An Lin;C. Merkel;Michelle A. DeMers;Ping-Ping Qu-Ping;E. Webb;Feixue Fu;D. Hutchins
在氮有限的亚热带环流中，固氮蓝藻，包括Crocosphaera，通过将二氮（N2）气体转化为氨来支持这些贫营养制度中的初级生产，提供了一个重要的生态系统服务。低纬度海洋中磷和铁的自然梯度制约着固氮生物的地理分布和活动，对海洋生态地球化学循环具有重要意义。Crocosphaera对多种营养限制的生理和分子反应仍有许多未知之处。我们培养了C. WatsonII在Fe、P和Fe/P（共）限制情况下将细胞生理学与diel基因表达联系起来，并观察到每种处理的独特生理学和转录谱。相反，在Fe/P共同限制下，Fe或P限制下降低的生长和N2固定资源利用效率（RUE）得到缓解。差异基因表达分析表明，Fe/P共同限制的细胞采用相同的反应，作为单一营养限制的细胞，减少细胞的营养需求和增加对环境变化的反应，包括较小的细胞大小，蛋白质周转（铁限制），和上调的环境感知和响应系统（P限制）。结合起来，这些机制增强了Fe/P共限制细胞的生长和RUE。这些发现对于我们理解N2固定的营养控制以及变化的海洋中初级生产力和微生物动力学的影响非常重要。
In the nitrogen-limited subtropical gyres, diazotrophic cyanobacteria, includingCrocosphaera, provide an essential ecosystem service by converting dinitrogen (N2) gas into ammonia to support primary production in these oligotrophic regimes. Natural gradients of phosphorus (P) and iron (Fe) availability in the low-latitude oceans constrain the biogeography and activity of diazotrophs with important implications for marine biogeochemical cycling. Much remains unknown regardingCrocosphaera’s physiological and molecular responses to multiple nutrient limitations. We culturedC. watsoniiunder Fe, P, and Fe/P (co)-limiting scenarios to link cellular physiology with diel gene expression and observed unique physiological and transcriptional profiles for each treatment. Counterintuitively, reduced growth and N2fixation resource use efficiencies (RUEs) for Fe or P under P limitation were alleviated under Fe/P co-limitation. Differential gene expression analyses show that Fe/P co-limited cells employ the same responses as single-nutrient limited cells that reduce cellular nutrient requirements and increase responsiveness to environmental change including smaller cell size, protein turnover (Fe-limited), and upregulation of environmental sense-and-respond systems (P-limited). Combined, these mechanisms enhance growth and RUEs in Fe/P co-limited cells. These findings are important to our understanding of nutrient controls on N2fixation and the implications for primary productivity and microbial dynamics in a changing ocean.