Symbiotic relationships between vestimentiferan tubeworms and chemosynthetic Gammaproteobacteria build the foundations of many hydrothermal vent and hydrocarbon seep ecosystems in the deep sea. The association between the vent tubeworm Riftia pachyptila and its endosymbiont Candidatus Endoriftia persephone has become a model system for symbiosis research in deep‐sea vestimentiferans, while markedly fewer studies have investigated symbiotic relationships in other tubeworm species, especially at cold seeps. Here we sequenced the endosymbiont genome of the tubeworm Lamellibrachia barhami from a cold seep in the Gulf of California, using short‐ and long‐read sequencing technologies in combination with Hi‐C and Dovetail Chicago libraries. Our final assembly had a size of ~4.17 MB, a GC content of 54.54%, 137X coverage, 4153 coding sequences, and a CheckM completeness score of 97.19%. A single scaffold contained 99.51% of the genome. Comparative genomic analyses indicated that the L. barhami symbiont shares a set of core genes and many metabolic pathways with other vestimentiferan symbionts, while containing 433 unique gene clusters that comprised a variety of transposases, defence‐related genes and a lineage‐specific CRISPR/Cas3 system. This assembly represents the most contiguous tubeworm symbiont genome resource to date and will be particularly valuable for future comparative genomic studies investigating structural genome evolution, physiological adaptations and host‐symbiont communication in chemosynthetic animal‐microbe symbioses.

中文翻译：

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冷渗液性结核杆菌Lamellibrachia barhami的化学合成γ-蛋白细菌内共生体的高连续性基因组装配

前卫鞭毛虫与化学合成的γ-变形细菌之间的共生关系为深海中许多热液喷口和碳氢化合物渗漏生态系统奠定了基础。之间的关联排气管虫Riftia pachyptila及其共生菌暂定Endoriftia珀尔塞福涅已成为深海vestimentiferans共生研究的模型系统，同时显着较少的研究探讨了在其它管虫物种共生关系，尤其是在冷泉。在这里，我们对结核杆菌Lamellibrachia barhami的内共生体基因组进行了测序使用短读和长读测序技术，结合Hi-C和Dovetail Chicago库，从加利福尼亚湾的一个冷泉中提取。我们的最终程序集的大小约为4.17 MB，GC含量为54.54％，覆盖率为137X，编码序列为4153，CheckM完整性评分为97.19％。单个支架包含99.51％的基因组。比较基因组分析表明，巴氏乳杆菌symbiont与其他vestimentiferan共生体共享一组核心基因和许多代谢途径，同时包含433​​个独特的基因簇，其中包括各种转座酶，与防御相关的基因和谱系特异性的CRISPR / Cas3系统。该大会代表了迄今最连续的结核共生体基因组资源，对于今后在化学合成动物-微生物共生中调查结构基因组进化，生理适应性和宿主共生体交流的比较基因组研究中，将特别有价值。