Scottish Oceans Institute, University of St Andrews, St Andrews, UK.
Department of Veterinary Medicine, University of Alaska Fairbanks, Fairbanks, AK, USA.
BMC Vet Res. 2024 Aug 1;20(1):340. doi: 10.1186/s12917-024-04125-5.
Understanding the relationship between resident microbiota and disease in cultured fish represents an important and emerging area of study. Marine gill disorders in particular are considered an important challenge to Atlantic salmon (Salmo salar) aquaculture, however relatively little is known regarding the role resident gill microbiota might play in providing protection from or potentiating different gill diseases. Here, 16S rRNA sequencing was used to examine the gill microbiome alongside fish health screening in farmed Atlantic salmon. Results were used to explore the relationship between microbial communities and gill disease.
Microbial community restructuring was observed throughout the sampling period and linked to varied drivers of change, including environmental conditions and severity of gill pathology. Taxa with significantly greater relative abundance on healthier gills included isolates within genus Shewanella, and taxa within family Procabacteriaceae. In contrast, altered abundance of Candidatus Branchiomonas and Rubritalea spp. were associated with damaged gills. Interestingly, more general changes in community richness and diversity were not associated with altered gill health, and thus not apparently deleterious to fish. Gross and histological gill scoring demonstrated seasonal shifts in gill pathology, with increased severity of gill damage in autumn. Specific infectious causes that contributed to observed pathology within the population included the gill disorder amoebic gill disease (AGD), however due to the uncontrolled nature of this study and likely mixed contribution of various causes of gill disease to observed pathology results do not strongly support an association between the microbial community and specific infectious or non-infectious drivers of gill pathology.
Results suggest that the microbial community of farmed Atlantic salmon gills undergo continual restructuring in the marine environment, with mixed influences upon this change including environmental, host, and pathogenic factors. A significant association of specific taxa with different gill health states suggests these taxa might make meaningful indicators of gill health. Further research with more frequent sampling and deliberate manipulation of gills would provide important advancement of knowledge in this area. Overall, although much is still to be learnt regarding what constitutes a healthy or maladapted gill microbial community, the results of this study provide clear advancement of the field, providing new insight into the microbial community structure of gills during an annual production cycle of marine-stage farmed Atlantic salmon.
了解养殖鱼类中居民微生物组与疾病之间的关系是一个重要且新兴的研究领域。特别是海洋鱼类鳃部疾病被认为是大西洋鲑（Salmo salar）养殖的重要挑战，然而，关于居民鳃部微生物组在提供保护或促进不同鳃部疾病方面可能发挥的作用，人们知之甚少。在这里，使用 16S rRNA 测序技术来检测养殖大西洋鲑的鳃部微生物组以及鱼类健康筛查。结果用于探索微生物群落与鳃部疾病之间的关系。
在整个采样期间观察到微生物群落结构的重构，并与各种变化驱动因素相关联，包括环境条件和鳃部病理学的严重程度。在更健康的鳃部上相对丰度更高的分类群包括希瓦氏菌属（Shewanella）和 Procabacteriaceae 科内的分离株。相比之下，变形菌门（Branchiomonas）和红杆菌属（Rubritalea）的丰度改变与受损的鳃部有关。有趣的是，群落丰富度和多样性的更普遍变化与改变的鳃部健康状况无关，因此对鱼类没有明显的危害。总鳃和组织学评分显示出鳃部病理学的季节性变化，秋季鳃部损伤的严重程度增加。导致群体中观察到的病理学的特定传染性原因包括鳃部疾病阿米巴性鳃病（AGD），但是由于本研究的非控制性以及可能对观察到的病理学结果有各种鳃部疾病原因的混合贡献，结果并不强烈支持微生物群落与鳃部病理学的特定传染性或非传染性驱动因素之间的关联。
结果表明，养殖大西洋鲑的鳃部微生物群落会在海洋环境中不断重构，这种变化的混合影响包括环境、宿主和致病性因素。特定分类群与不同鳃部健康状态的显著关联表明这些分类群可能成为鳃部健康的有意义的指标。通过更频繁的采样和有针对性的鳃部处理进行进一步研究将为该领域的知识提供重要进展。总体而言，尽管关于什么构成健康或适应不良的鳃部微生物群落还有很多需要了解，但本研究的结果提供了该领域的明确进展，为海洋养殖阶段的养殖大西洋鲑的年度生产周期中的鳃部微生物群落结构提供了新的见解。
