SAR86 is one of the most abundant groups of bacteria in the global surface ocean. However, since its discovery over 30 years ago, it has remained recalcitrant to isolation and many details regarding this group are still unknown. Here we report the cellular characteristics from the first SAR86 isolate brought into culture, Magnimaribacter mokuoloeensis strain HIMB1674, and use its closed genome in concert with over 700 environmental genomes to assess the phylogenomic and functional characteristics of this order-level lineage of marine Gammaproteobacteria. The SAR86 order Magnimaribacterales invest significant genomic resources into the capacity for $\beta$-oxidation, which is present in most genomes in high gene copy numbers. This cyclical set of reactions appears to be fed by components of cell membranes that include lipids such as phosphatidylcholine, phosphatidylethanolamine, glycolipids, and sulfolipids. In addition to the widespread capacity to degrade the side chain of steroidal compounds via $\beta$-oxidation, several SAR86 sublineages also appear able to fully degrade the steroid polycyclic ring structure as well as other aromatic, polycyclic, and heterocyclic molecules. Read recruitment from publicly available metagenomes reveals that the Magnimaribacterales compose up to 6% of the global surface ocean microbial community. Only a subset of genera drive these high relative abundances, with some more globally dominant and others restricted to specific oceanic regions. This study provides an unprecedented foundation through which to understand this highly abundant yet poorly understood lineage of marine bacteria, and charts a path to bring more representatives of this order into laboratory culture.

中文翻译：

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分离物锚定比较揭示了 SAR86 海洋细菌的进化和功能差异


SAR86 是全球表层海洋中最丰富的细菌群之一。然而，自 30 多年前被发现以来，它一直不愿与世隔绝，有关该组的许多细节仍然未知。在这里，我们报告了第一个进入培养物的 SAR86 分离株 Magnimaribacter mokuoloeensis 菌株 HIMB1674 的细胞特征，并使用其封闭基因组与 700 多个环境基因组来评估海洋 Gammaproteobacteria 的这一顺序级谱系的系统发育和功能特征。SAR86 目 Magnimaribacterales 将大量基因组资源投入到 $\beta$-氧化能力中，这在大多数基因组中以高基因拷贝数存在。这组循环反应似乎由细胞膜成分提供，其中包括脂质，如磷脂酰胆碱、磷脂酰乙醇胺、糖脂和磺脂。除了通过 $\beta$-氧化降解甾体化合物侧链的广泛能力外，一些 SAR86 亚系似乎也能够完全降解类固醇多环结构以及其他芳香族、多环和杂环分子。从公开可用的宏基因组中读取招募显示，Magnimaribacterales 占全球表层海洋微生物群落的 6%。只有一部分属驱动着这些高相对丰度，其中一些更在全球范围内占主导地位，而另一些则仅限于特定的海洋区域。这项研究为理解这种高度丰富但知之甚少的海洋细菌谱系提供了一个前所未有的基础，并为将该目的的更多代表带入实验室培养开辟了一条道路。