The basal metazoan phylum, Porifera (sponges), is increasingly used as a model to investigate ecological and evolutionary features of microbe-animal symbioses. However, sponges often host complex microbiomes, which has hampered our understanding of their interactions with their microbial symbionts. Here, we describe the discovery and characterisation of the simplest sponge holobiont reported to date, consisting of the deep-sea glass sponge Aphrocalistes beatrix and two newly described microbial symbionts: an autotrophic ammonia-oxidising archaeon and a bacterial heterotroph. Omics analyses and metabolic modelling revealed the dependency of the ammonia-oxidising archaea on sponge-derived ammonia to drive primary production, which in turn supports the bacterium’s growth by providing the dicarboxylate fumarate. Furthermore, virus-mediated archaeal lysis appears crucial to overcome the bacterium’s vitamin B12 auxotrophy. These findings reveal that the exchange of vitamin B12 and dicarboxylate may be evolutionarily conserved features of symbiosis as they can also be found in interactions between free-living marine bacteria, and between microbes and plants or diatoms.

中文翻译：

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简单的 Porifera 全息揭示了宿主、古细菌、细菌和噬菌体之间的复杂相互作用


基底后生动物门 Porifera（海绵）越来越多地被用作研究微生物-动物共生的生态和进化特征的模型。然而，海绵通常承载着复杂的微生物组，这阻碍了我们对它们与微生物共生体相互作用的理解。在这里，我们描述了迄今为止报道的最简单的海绵全息生物的发现和表征，由深海玻璃海绵 Aphrocalistes beatrix 和两种新描述的微生物共生体组成：自养氨氧化古细菌和细菌异养菌。组学分析和代谢模型揭示了氨氧化古细菌对海绵衍生氨的依赖性，以驱动初级生产，这反过来又通过提供富马酸二羧酸盐来支持细菌的生长。此外，病毒介导的古细菌裂解似乎对于克服细菌的维生素 B12 营养缺陷至关重要。这些发现表明，维生素 B12 和二羧酸盐的交换可能是共生的进化保守特征，因为它们也可以在自由生活的海洋细菌之间以及微生物与植物或硅藻之间的相互作用中找到。