Table_1_Unveiling microbiome signature in inner body fluids: comparison between wild and aquarium small-spotted catshark (Scyliorhinus canicula).docx

The microbiome is a crucial influencer in animal development, immune function and health, and it has complex and dynamic interactions with the environment, but little is known about the microbial signatures of inner body fluids. Recent evidence suggests that inner body fluids could be an indicator of the environmental interactions that fish experience. In the present study, we provide a comparative analysis of the microbial profile found in small-spotted catsharks’ blood plasma and seminal plasma and how microbial signatures vary between aquarium and wild animals. In the blood plasma microbiome, the habitat did not affect the α- and β-diversity, while in seminal plasma, both α- and β-diversity differed between both habitats. Proteobacteria are the main bacteria dominated independently the inner body fluid and habitats. No core microbiome was identified at the genus level, with only Pseudomonas and Cloacibacterium present in both inner body fluids and habitats. Of the 14 genera identified in blood plasma, only four were shared between habitats (making up 45.17% and 51.03% of relative abundance for wild and aquarium, respectively). Similarly, of the 100 genera identified in seminal plasma, only 41 were shared between habitats (84.79% and 64.83%, respectively). Moreover, in the seminal plasma, using ANCOM approaches, Serratia, Salinisphaera and Cutibacterium were found significantly enriched in aquarium animals. None potentially pathogenic bacteria were identified in the blood samples, while Coxiella, Prevotella, Coprococcus, Haemophilus and Phocoenobacter were potentially pathogenic bacteria identified in the seminal plasma samples. In summary, this study provides evidence of a circulating blood and seminal plasma microbiome in healthy small-spotted catsharks. Furthermore, dynamic changes were observed in the microbiome of these inner body fluids, which differed between the aquarium and wild habitats.

微生物组（microbiome）是影响动物发育、免疫功能与健康状态的关键因子，且其与环境间存在复杂且动态的互作关系，但目前学界对动物体内体液的微生物特征仍知之甚少。最新研究证据表明，鱼类体内体液可作为其所处环境互作状态的指示物。本研究针对小斑猫鲨（small-spotted catsharks）的血浆与精浆中的微生物群落特征展开对比分析，并探究圈养与野生两种生境下其微生物特征的差异变化。血浆微生物组的生境并不会对α多样性与β多样性产生显著影响，但精浆微生物组的α、β多样性在两种生境间均存在显著差异。无论体内体液类型与生境如何，变形菌门（Proteobacteria）均为优势菌门。在属水平未鉴定到核心微生物组，仅假单胞菌属（Pseudomonas）与阴沟杆菌属（Cloacibacterium）在两种体内体液及两种生境中均有检出。在血浆中鉴定出的14个菌属中，仅4个在两种生境间共享，其在野生与圈养个体中的相对丰度占比分别为45.17%与51.03%。同理，在精浆中鉴定出的100个菌属中，仅41个在两种生境间共享，其相对丰度占比分别为84.79%与64.83%。此外，通过ANCOM分析方法，研究人员发现圈养个体的精浆中沙雷氏菌属（Serratia）、盐孢菌属（Salinisphaera）与Cutibacterium属的相对丰度显著升高。血浆样本中未检出潜在致病菌，而精浆样本中则检测到柯克斯体属（Coxiella）、普雷沃氏菌属（Prevotella）、粪球菌属（Coprococcus）、嗜血杆菌属（Haemophilus）与海豚杆菌属（Phocoenobacter）五类潜在致病菌。综上，本研究证实健康小斑猫鲨的血浆与精浆中存在循环微生物组。此外，这类体内体液的微生物组存在动态变化，且其群落特征在圈养与野生生境间存在显著差异。