两种养殖模式下黄条鰤幼鱼消化道菌群对生长的微生态调控作用

探究了工厂化、网箱养殖模式对黄条鰤(Seriola lalandi)幼鱼生长性能及消化道菌群的影响, 通过 16S rRNA 高通量测序和生物信息学方法, 分析了两种养殖模式下黄条鰤幼鱼消化道(胃、幽门盲囊、肠道)、饵料及养殖水中的菌群结构特征及其互作关系。结果显示, 本实验条件下, 网箱养殖黄条鰤幼鱼较工厂化养殖鱼生长性能显著提升; 在黄条鰤幼鱼消化道菌群方面, 门水平上的拟杆菌门(Bacteroidetes)、厚壁菌门(Firmicutes)和属水平上的拟普雷沃氏菌属(Alloprevotella)、拟杆菌属(Bacteroides)在网箱养殖模式中其丰度值高于工厂化养殖模式, 其中拟杆菌属仅出现于网箱养殖模式且呈现显著性差异; Beta 多样性分析显示消化道菌群更多受到饵料菌群的影响, 受水环境影响相对较小。KEGG 注释分析表明两种养殖模式的差异菌群中, 网箱养殖幼鱼消化道菌群主要参与磷酸转移酶系统 (PTS)和 NOD 样受体信号通路, 而工厂化养殖幼鱼为碳水化合物代谢和类胡萝卜素合成通路。本研究表明, 环境菌群中, 饵料菌群对消化道菌群的影响大于养殖水体菌群; 消化道微生物群落通过调整其组成结构从而改变菌群功能通路的方式, 积极参与两种养殖模式下黄条鰤幼鱼生长机能差异的调控。因此, 网箱养殖鱼表现出更快速的生长性能可能是由于机体内的菌群产生了更多的短链脂肪酸并诱导 IGF-1 等生长相关功能基因的表达, 从而促进机体的营养吸收和生长。本研究预期结果将为黄条鰤专用配合饲料的研制和健康养殖技术开发提供微生态理论支撑。

Microecological regulation of gastrointestinal microflora in the growth of yellowtail kingfish (Seriola lalandi) juveniles under indoor tank culture and cage culture modes

Growth is one of the most important economic traits in aquaculture and is directly related to the financial benefits of farming. It is influenced by a number of factors, including genetic and environmental factors. When faced with different environments, fish growth is not only regulated by their own physiological conditions but also by symbionts, such as gastrointestinal microbiota. To investigate the differences in the growth of yellowtail kingfish juveniles under two culture modes, namely indoor tank and deep sea cage culture, and their relationship with gastrointestinal flora, as well as with feed microbiota and culture water microbiota, six-month-old fish of the same size at (17.23±0.99) cm and body mass at (77.44±11.58) g were selected for a 30-day culture experiment under these two culture modes. The differences in the rate of yellowtail kingfish juvenile growth under these two culture modes were recorded. The structure and abundance of gastrointestinal microbiota (stomach, pyloric blind sac, and intestine), as well as feed and culture water microbiota, were analyzed by 16S rRNA high-throughput sequencing and bioinformatic analysis. The results showed that the growth of cage cultured juvenile yellowtail kingfish was significantly faster than that of indoor tank cultured fish. As for the gastrointestinal microbiota of juveniles cultured in cage, the abundance of Bacteroidetes and Firmicutes at the phylum level, as well as the abundance of Alloprevotella and Bacteroides at the genus level, were higher than in indoor tank cultured fish, wherein the abundance of Bacteroides was significantly higher. The composition of the gastrointestinal microbiota of the indoor tank cultured fish was different from that of the feed microbiota and significantly different from that of culture water microbiota, whereas the composition of the gastrointestinal microbiota of fish from cage culture was more similar with that of the feed microbiota but also significantly different from that of the culture water microbiota. Beta diversity analysis showed that the gastrointestinal microbiota of juvenile yellowtail kingfish was more influenced by feed microbiota and less by the culture water bacterial community. KEGG annotation analysis showed that the main functional pathways involved in the gastrointestinal microbiota of juvenile yellowtail kingfish in the cage culture were the phosphotransferase system (PTS) and NOD-like receptor signaling pathway, whereas carbohydrate metabolism and the carotenoid biosynthesis pathway were found in the indoor tank cultured fish. These results indicate that the gastrointestinal microbiota regulate the growth of yellowtail kingfish juveniles under indoor tank and cage culture conditions by changing their structure and abundance, as well as via functional pathways. Moreover, feed microbiota had a greater influence on gastrointestinal microbiota than culture water microbiota. According to these results, the faster growth of cage cultured fish may be due to the production of more short-chain fatty acid (SCFA) by gastrointestinal microbiota (e.g., Alloprevotella and Bacteroides) to induce the production of insulin-like growth factor 1 (IGF-1). These findings provide micro-ecological support for high-efficient commercial feed and healthy culture technology for yellowtail kingfish.