To identify novel cross-domain symbiosis between Candidatus Patescibacteria and Archaea, we performed fluorescence in situ hybridization (FISH) on enrichment cultures derived from methanogenic bioreactor sludge with the newly designed 32-520-1066 probe targeting the family-level uncultured clade 32-520/UBA5633 lineage in the class Ca. Paceibacteria. All FISH-detectable 32-520/UBA5633 cells were attached to Methanospirillum, indicating high host specificity. Transmission electron microscopy observations revealed 32-520/UBA5633-like cells that were specifically adherent to the plug structure of Methanospirillum-like rod-shaped cells. The metagenome-assembled genomes of 32-520/UBA5633 encoded unique gene clusters comprising pilin signal peptides and type IV pilins. These results provide novel insights into unseen symbiosis between Ca. Patescibacteria and Archaea.

中文翻译：

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在产甲烷生态系统中发现的 Candidatus Patescibacteria 和产氢产甲烷古菌 Methanospirillum 之间的新型跨域共生。

为了鉴定 Candidatus Patescibacteria 和古细菌之间的新型跨域共生关系，我们使用新设计的 32-520-1066 探针对来自产甲烷生物反应器污泥的富集培养物进行了荧光原位杂交 (FISH)，靶向家族级未培养的进化枝 32-520 /UBA5633 Ca 类中的谱系。和平杆菌。所有 FISH 可检测的 32-520/UBA5633 细胞都附着在甲烷螺菌上，表明宿主特异性高。透射电子显微镜观察显示 32-520/UBA5633 样细胞特异性粘附于 Methanospirillum 样杆状细胞的栓塞结构。32-520/UBA5633 的宏基因组组装基因组编码独特的基因簇，包括菌毛蛋白信号肽和 IV 型菌毛蛋白。这些结果为 Ca 之间看不见的共生提供了新的见解。