Diazotrophs provide a significant reactive nitrogen source in the ocean. Increased warming and stratification may decrease nutrient availability in the future, forcing microbial communities toward using dissolved organic matter (DOM). Not depending on reactive nitrogen availability, diazotrophs may be “winners” in a nutrient‐depleted ocean. However, their ability to exploit DOM may influence this success. We exposed cultures of the widespread Crocosphaera to low (26°C, pH 8.1), moderate (28°C, pH 8.0), and extreme (30°C, pH 7.9) climate change scenarios, under control or DOM‐amended conditions. Growth was suboptimal in the low and extreme treatments and favored in the moderate treatment. DOM was preferred as a carbon source regardless of the treatment and promoted N2 fixation in extreme conditions. This was reflected in the increased expression of photosynthesis genes to obtain energy. DOM provides Crocosphaera with a key ecological advantage, possibly dictating diazotroph‐derived nitrogen inputs in the future ocean.

中文翻译：

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溶解的有机物抵消了气候变化对固氮蓝细菌 Crocosphaera 的不利影响

固氮生物在海洋中提供了重要的活性氮源。变暖和分层的加剧可能会减少未来养分的可用性，迫使微生物群落使用溶解有机物（DOM）。不依赖于活性氮的可用性，固氮生物可能是营养耗尽的海洋中的“赢家”。然而，他们利用 DOM 的能力可能会影响这一成功。我们暴露了广泛存在的文化鳄鱼球菌属在受控或 DOM 修正条件下，低（26°C，pH 8.1）、中度（28°C，pH 8.0）和极端（30°C，pH 7.9）气候变化情景。在低度和极端处理中生长不是最理想的，而在中等处理中则有利于生长。无论处理如何，DOM 都是首选碳源，并促进 N2极端条件下的固定。这反映在为了获取能量而进行的光合作用基因的表达增加。DOM 提供鳄鱼球菌属具有关键的生态优势，可能决定未来海洋中固氮生物衍生的氮输入。