Influence of Essential Oils in Diet and Life-Stage on Gut Microbiota and Fillet Quality of Rainbow Trout

Developing fish farming to meet the demands of food security and sustainability in the 21st century will require new farming systems and improved feeds. Diet and microbe interactions in the gut is an important variable with the potential to make a significant impact on future fish farming diets and production systems. It was monitored the gut microbiota of farmed rainbow trout using 16S rRNA profiling over 51 weeks during standard rearing conditions and feeding diet with supplementation of an essential oils (MixOil) mixture from plants (at a concentration in diet of 200 ppm). Gut microbiota 16S rRNA profiling indicated that the fish gut was dominated by Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes. Although the dietary supplementation with MixOil had no impact on either the composition or architecture of gut microbiota, significant changes in alpha and beta diversity and relative abundance of groups of gut bacteria were evident during growth stages on test feeds, especially upon prolonged growth on finishing feed. Fish fillet quality to guarantee palatability and safety for human consumption was also evaluated. Significant differences within the gut microbiota of juvenile and adult trout under the same rearing conditions were observed, highlighting the need for further studies examining how dietary microbiome modulation at different life stages can influence animal health, production yields and final product quality.

为满足21世纪粮食安全与可持续发展的需求，水产养殖业的发展亟需新型养殖模式与改良饲料。肠道内日粮与微生物的互作是一项关键变量，有望对未来水产养殖日粮及生产体系产生重大影响。本研究在标准养殖条件下，对饲喂添加植物源精油混合物（MixOil，日粮添加浓度为200 ppm）日粮的养殖虹鳟，采用16S rRNA基因谱分析（16S rRNA profiling）技术开展了为期51周的肠道微生物组（gut microbiota）监测。肠道微生物组16S rRNA基因谱分析结果显示，虹鳟肠道菌群以放线菌门（Actinobacteria）、变形菌门（Proteobacteria）、拟杆菌门（Bacteroidetes）以及厚壁菌门（Firmicutes）为优势类群。尽管日粮添加MixOil对肠道菌群的组成与结构均无显著影响，但在试验饲料饲喂的生长阶段，尤其是育肥期长期饲喂后，肠道菌群的α多样性（alpha diversity）、β多样性（beta diversity）以及各细菌类群的相对丰度均发生了显著变化。本研究同时评估了可保障人类食用适口性与安全性的虹鳟鱼肉品质。本研究发现，在相同养殖条件下，幼龄与成年虹鳟的肠道菌群存在显著差异，这凸显了开展进一步研究的必要性，以明确不同生命阶段的日粮微生物组调控如何影响动物健康、生产性能及最终产品品质。