The core properties of microbial genomes, including GC content and genome size, are known to vary widely among different bacteria and archaea ^1,2 . Several hypotheses have been proposed to explain this genomic variability, but the fundamental drivers that shape bacterial and archaeal genomic properties remain uncertain ^3-7 . Here, we report the existence of a sharp genomic transition zone below the photic zone, where bacterial and archaeal genomes and proteomes undergo a community-wide punctuated shift. Across a narrow range of increasing depth of just tens of metres, diverse microbial clades trend towards larger genome size, higher genomic GC content, and proteins with higher nitrogen but lower carbon content. These community-wide changes in genome features appear to be driven by gradients in the surrounding environmental energy and nutrient fields. Collectively, our data support hypotheses invoking nutrient limitation as a central driver in the evolution of core bacterial and archaeal genomic and proteomic properties.

中文翻译：

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海洋内部微生物基因组过渡区的环境驱动因素。

已知微生物基因组的核心特性，包括GC含量和基因组大小，在不同细菌和古细菌^1,2之间差异很大。已经提出了几种假设来解释这种基因组变异性，但是影响细菌和古细菌基因组特性的基本驱动因素仍然不确定^3-7。在这里，我们报告了在光合区下方存在一个尖锐的基因组过渡区，在该区中细菌和古细菌基因组和蛋白质组经历了整个社区范围内的标点移位。在仅有几十米的增加深度的狭窄范围内，各种各样的微生物进化趋向于更大的基因组大小，更高的基因组GC含量以及具有更高氮含量但碳含量更低的蛋白质。这些社区范围内基因组特征的变化似乎是由周围环境能量和养分场中的梯度驱动的。总的来说，我们的数据支持假设营养限制是核心细菌和古细菌基因组和蛋白质组学特性演变的主要驱动力。