Mixotrophic protists combine photosynthesis with the ingestion of prey to thrive in resource-limited conditions in the ocean. Yet, how they fine-tune resource investments between their two different metabolic strategies remains unclear. Here, we present a modeling framework (Mixotroph Optimal Contributions to Heterotrophy and Autotrophy) that predicts the optimal (growth-maximizing) investments of carbon and nitrogen as a function of environmental conditions. Our model captures a full spectrum of trophic modes, in which the optimal investments reflect zero-waste solutions (i.e., growth is colimited by carbon and nitrogen) and accurately reproduces experimental results. By fitting the model to data for Ochromonas , we were able to predict metabolic strategies at a global scale. We find that high phagotrophic investment is the dominant strategy across different oceanic biomes, used primarily for nitrogen acquisition. Our results therefore support empirical observations of the importance of mixotrophic grazers to upper ocean bacterivory.

中文翻译：

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预测全球海洋中的最佳混合营养代谢策略


混合营养原生生物将光合作用与摄入猎物相结合，在海洋资源有限的条件下茁壮成长。然而，他们如何在两种不同的代谢策略之间微调资源投资仍不清楚。在这里，我们提出了一个建模框架 （Mixotroph Optimal Contributions to Heterotrophy and Autotrophy），该框架预测碳和氮的最佳（生长最大化）投资作为环境条件的函数。我们的模型捕获了全方位的营养模式，其中最佳投资反映了零浪费解决方案（即生长受碳和氮的共同限制）并准确再现了实验结果。通过将模型拟合到 Ochromonas 的数据，我们能够在全球范围内预测代谢策略。我们发现，高吞噬投资是不同海洋生物群落的主要策略，主要用于氮获取。因此，我们的结果支持了对混合营养食草动物对上层海洋细菌食菌重要性的实证观察。