Table_5_Unveiling microbiome signature in inner body fluids: comparison between wild and aquarium small-spotted catshark (Scyliorhinus canicula).xlsx

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素，且其与环境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。近期研究证据表明，体内体液可作为鱼类所经历的环境互作的指示指标。本研究对小斑猫鲨（small-spotted catsharks）的血浆与精浆中的微生物群落特征进行了比较分析，并探究了圈养与野生个体间的微生物特征差异。在血浆微生物组中，生存环境并未对α多样性（α-diversity）与β多样性（β-diversity）产生显著影响；而在精浆微生物组中，圈养与野生个体的α、β多样性均存在显著差异。无论体内体液类型与生存环境如何，变形菌门（Proteobacteria）均为优势菌群。在属水平上未检测到核心微生物组，仅假单胞菌属（Pseudomonas）与阴沟杆菌属（Cloacibacterium）在两类体内体液以及两种生境的样本中均有检出。在血浆样本中检出的14个菌属中，仅4个菌属在两种生境的个体间共享，这4个菌属分别占野生与圈养个体血浆菌群相对丰度的45.17%与51.03%。类似地，在精浆样本中检出的100个菌属中，仅41个菌属在两种生境间共享，其相对丰度分别占野生与圈养个体精浆菌群的84.79%与64.83%。此外，通过ANCOM分析方法发现，圈养个体的精浆中沙雷氏菌属（Serratia）、盐孢菌属（Salinisphaera）与棒状杆菌属（Cutibacterium）的相对丰度显著升高。血浆样本中未检出潜在致病菌，而精浆样本中则检出了柯克斯体属（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）等潜在致病菌。综上，本研究证实健康小斑猫鲨的循环血浆与精浆中均存在微生物组；此外，两类体内体液的微生物组均存在动态变化，且圈养与野生个体间的微生物组特征存在显著差异。