Red Sea Research Center, Division of Biological and Environmental Science and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA.
Sci Rep. 2017 Jan 17;7:40579. doi: 10.1038/srep40579.
Endozoicomonas bacteria are globally distributed and often abundantly associated with diverse marine hosts including reef-building corals, yet their function remains unknown. In this study we generated novel Endozoicomonas genomes from single cells and metagenomes obtained directly from the corals Stylophora pistillata, Pocillopora verrucosa, and Acropora humilis. We then compared these culture-independent genomes to existing genomes of bacterial isolates acquired from a sponge, sea slug, and coral to examine the functional landscape of this enigmatic genus. Sequencing and analysis of single cells and metagenomes resulted in four novel genomes with 60-76% and 81-90% genome completeness, respectively. These data also confirmed that Endozoicomonas genomes are large and are not streamlined for an obligate endosymbiotic lifestyle, implying that they have free-living stages. All genomes show an enrichment of genes associated with carbon sugar transport and utilization and protein secretion, potentially indicating that Endozoicomonas contribute to the cycling of carbohydrates and the provision of proteins to their respective hosts. Importantly, besides these commonalities, the genomes showed evidence for differential functional specificity and diversification, including genes for the production of amino acids. Given this metabolic diversity of Endozoicomonas we propose that different genotypes play disparate roles and have diversified in concert with their hosts.
内共生菌在全球范围内广泛分布，通常与包括造礁珊瑚在内的各种海洋宿主大量共生，但它们的功能仍不清楚。在本研究中，我们从单细胞和直接从珊瑚 Stylophora pistillata、Pocillopora verrucosa 和 Acropora humilis 中获得的宏基因组中生成了新的内共生菌基因组。然后，我们将这些与培养无关的基因组与从海绵、海蛞蝓和珊瑚中获得的细菌分离株的现有基因组进行比较，以研究这个神秘属的功能景观。对单细胞和宏基因组的测序和分析产生了四个新的基因组，其基因组完整度分别为 60-76% 和 81-90%。这些数据还证实，内共生菌基因组很大，并且没有为专性内共生生活方式而精简，这意味着它们有自由生活阶段。所有基因组都显示出与碳糖运输和利用以及蛋白质分泌相关的基因富集，这可能表明内共生菌有助于碳水化合物的循环和为其各自的宿主提供蛋白质。重要的是，除了这些共同之处，基因组还显示出功能特异性和多样化的证据，包括产生氨基酸的基因。鉴于内共生菌的这种代谢多样性，我们提出不同的基因型可能发挥不同的作用，并与它们的宿主一起多样化。
