Costa Rúben M, Cárdenas Anny, Loussert-Fonta Céline, Toullec Gaëlle, Meibom Anders, Voolstra Christian R
Division of Biological and Environmental Science and Engineering, Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
Department of Biology, University of Konstanz, Konstanz, Germany.
Front Microbiol. 2021 Apr 8;12:637834. doi: 10.3389/fmicb.2021.637834. eCollection 2021.
Aiptasia is an emerging model organism to study cnidarian symbioses due to its taxonomic relatedness to other anthozoans such as stony corals and similarities of its microalgal and bacterial partners, complementing the existing (Hydrozoa) and (Anthozoa) model systems. Despite the availability of studies characterizing the microbiomes of several natural Aiptasia populations and laboratory strains, knowledge on basic information, such as surface topography, bacterial carrying capacity, or the prospect of microbiome manipulation is lacking. Here we address these knowledge gaps. Our results show that the surface topographies of the model hydrozoan and anthozoans differ substantially, whereas the ultrastructural surface architecture of Aiptasia and stony corals is highly similar. Further, we determined a bacterial carrying capacity of ∼10 and ∼10 bacteria (i.e., colony forming units, CFUs) per polyp for aposymbiotic and symbiotic Aiptasia anemones, respectively, suggesting that the symbiotic status changes bacterial association/density. Microbiome transplants from and sp. to gnotobiotic Aiptasia showed that only a few foreign bacterial taxa were effective colonizers. Our results shed light on the putative difficulties of transplanting microbiomes between cnidarians in a manner that consistently changes microbial host association at large. At the same time, our study provides an avenue to identify bacterial taxa that exhibit broad ability to colonize different hosts as a starting point for cross-species microbiome manipulation. Our work is relevant in the context of microbial therapy (probiotics) and microbiome manipulation in corals and answers to the need of having cnidarian model systems to test the function of bacteria and their effect on holobiont biology. Taken together, we provide important foundation data to extend Aiptasia as a coral model for bacterial functional studies.
由于艾氏海葵与石珊瑚等其他珊瑚虫纲动物在分类学上具有亲缘关系，且其微藻和细菌共生体具有相似性，因此它正成为研究刺胞动物共生关系的新兴模式生物，对现有的水螅纲和珊瑚虫纲模式系统起到了补充作用。尽管已有多项研究对几种天然艾氏海葵种群和实验室菌株的微生物群落进行了特征描述，但对于诸如表面形貌、细菌承载能力或微生物群落操控前景等基本信息仍缺乏了解。在此，我们填补这些知识空白。我们的研究结果表明，模式水螅纲动物和珊瑚虫纲动物的表面形貌存在显著差异，而艾氏海葵和石珊瑚的超微结构表面结构高度相似。此外，我们分别测定了无共生体和有共生体的艾氏海葵每只水螅体的细菌承载能力约为10⁶和10⁷个细菌（即菌落形成单位，CFU），这表明共生状态会改变细菌的关联/密度。将来自其他物种的微生物群落移植到无菌的艾氏海葵中表明，只有少数外来细菌类群是有效的定植者。我们的研究结果揭示了在刺胞动物之间移植微生物群落时，要以一种能在很大程度上持续改变微生物与宿主关联的方式存在的潜在困难。同时，我们的研究提供了一条途径，可用于识别具有广泛定植不同宿主能力的细菌类群，作为跨物种微生物群落操控的起点。我们的工作在珊瑚的微生物治疗（益生菌）和微生物群落操控背景下具有相关性，并且回应了需要有刺胞动物模式系统来测试细菌功能及其对共生体生物学影响的需求。综上所述，我们提供了重要的基础数据，以扩展艾氏海葵作为用于细菌功能研究的珊瑚模型。
