Corals engage in symbioses with micro‐organisms that provide nutrients and protect the host. Where the prokaryotic microbes perform their symbiotic functions within a coral is, however, poorly understood. Here, we studied the tissue‐specific microbiota of the coral Corallium rubrum by dissecting its tissues from the skeleton and separating the white polyps from the red‐coloured coenenchyme, followed by 16S rRNA gene metabarcoding of the three fractions. Dissection was facilitated by incubating coral fragments in RNAlater, which caused tissues to detach from the skeleton. Our results show compartmentalisation of the microbiota. Specifically, Endozoicomonas, Parcubacteria and a Gammaproteobacteria were primarily located in polyps, whereas Nitrincolaceae and one Spirochaeta phylotype were found mainly in the coenenchyme. The skeleton‐associated microbiota was distinct from the microbiota in the tissues. Given the difference in tissue colour and microbiota of the polyps and coenenchyme, we analysed the microbiota of three colormorphs of C. rubrum (red, pink, white), finding that the main difference was a very low abundance of Spirochaeta in white colormorphs. While the functions of C. rubrum's symbionts are unknown, their localisation within the colony suggests that microhabitats exist, and the presence of Spirochaeta appears to be linked to the colour of C. rubrum.

中文翻译：

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珍贵珊瑚 Corallium rubrum 的细菌共生体在菌落特定区室中的分布存在差异，并且颜色形态也有所不同

珊瑚与微生物共生，提供营养并保护宿主。然而，人们对原核微生物在珊瑚中发挥共生功能的地方知之甚少。在这里，我们研究了珊瑚的组织特异性微生物群红色珊瑚将其组织从骨骼上解剖出来，将白色息肉与红色的间质细胞分离，然后16S rRNA三个部分的基因元条形码。通过在 RNAlater 中孵育珊瑚碎片来促进解剖，这会导致组织从骨骼上分离。我们的结果显示了微生物群的划分。具体来说，内生单胞菌属、Parcubacteria 和 Gammaproteobacteria 主要位于息肉中，而 Nitrincolaceae 和一种螺旋体系统发育型主要发现于双烯体中。骨骼相关微生物群与组织中的微生物群不同。鉴于息肉和共烯质的组织颜色和微生物群的差异，我们分析了息肉和共烯质的三种颜色形态的微生物群红色 C. 红色（红色、粉色、白色），发现主要差异是丰度非常低螺旋体白色颜色变形。虽然功能红色 C. 红色的共生体是未知的，它们在群体内的定位表明微生境的存在，并且存在螺旋体似乎与颜色有关红色 C. 红色。