Department of Biology, The Pennsylvania State University, State College, PA, USA.
Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA.
Nat Commun. 2024 Nov 4;15(1):9508. doi: 10.1038/s41467-024-53855-5.
Microbes perform critical functions in corals, yet most knowledge is derived from the photic zone. Here, we discover two mollicutes that dominate the microbiome of the deep-sea octocoral, Callogorgia delta, and likely reside in the mesoglea. These symbionts are abundant across the host's range, absent in the water, and appear to be rare in sediments. Unlike other mollicutes, they lack all known fermentative capabilities, including glycolysis, and can only generate energy from arginine provided by the coral host. Their genomes feature several mechanisms to interact with foreign DNA, including extensive CRISPR arrays and restriction-modification systems, which may indicate their role in symbiosis. We propose the novel family Oceanoplasmataceae which includes these symbionts and others associated with five marine invertebrate phyla. Its exceptionally broad host range suggests that the diversity of this enigmatic family remains largely undiscovered. Oceanoplasmataceae genomes are the most highly reduced among mollicutes, providing new insight into their reductive evolution and the roles of coral symbionts.
微生物在珊瑚中发挥着关键作用，但大多数知识都是从光区获得的。在这里，我们发现了两种柔膜菌，它们主导着深海柳珊瑚 Callogorgia delta 的微生物组，并且可能存在于中胶层。这些共生体在宿主的分布范围内丰富存在，在水中不存在，在沉积物中似乎很少见。与其他柔膜菌不同，它们缺乏所有已知的发酵能力，包括糖酵解，并且只能从珊瑚宿主提供的精氨酸中产生能量。它们的基因组具有几种与外源 DNA 相互作用的机制，包括广泛的 CRISPR 阵列和限制修饰系统，这可能表明它们在共生中的作用。我们提出了一个新的科 Oceanoplasmataceae，其中包括这些共生体以及与五个海洋无脊椎动物门相关的其他共生体。它异常广泛的宿主范围表明，这个神秘家族的多样性在很大程度上仍未被发现。Oceanoplasmataceae 基因组是柔膜菌中最高度简化的，为它们的还原进化和珊瑚共生体的作用提供了新的见解。
