Abstract: Hexagrammos otakii is a kind of representative cold water fish with high value. Based on the analysis about microflora of the skin mucus and intestinal contents in H. otakii, the diversity of the microflora and the potential pathogenic microorganisms were studied. The genomic DNA of skin mucus and intestinal contents of H. otakii in facilities farm were extracted, the V3+V4 gene of different samples was analyzed by 16S rRNA high-throughput sequencing technology and biological analysis method. Results showed that there were only 33 common OTUs among different samples of skin mucus and intestinal contents. The Venn showed some similarities and differences among different samples. The rank abundance curve showed the homogeneity and richness of the samples, and these data were reasonable and reliable. The mean value of alpha index showed that the microbial richness of intestinal contents was high, and the species diversity of skin mucus was high; beta diversity showed the heterogeneity of different samples and the similarity of the same samples. At the phylum level, the dominant phylums were Cyanobacteria, Proteobacteria and Firmicutes. At the genus level, the core flora in intestinal contents included Streptophyta, Bacillus, Bacillaceae_unclassified, Aeromonas and Vibrio; while the core flora in skin mucus included Streptophyta, Aeromonas, Bacillaceae_unclassified, Myriudes, Gemmobacter and Vibrio. The heatmap showed the differences in the microbial species were biological functions, and the existence of conditional pathogens such as Bacillaceae_unclassified, Aeromonas, Vibrio, Gemmobacter might lead to the occurrence of diseases. In this study, the diversity and abundance of microorganisms and the characteristics of the main pathogenic bacteria in the skin mucus and intestinal contents were analyzed, which has an important significance for the healthy aquaculture and disease control of H. otakii.

Key words: Hexagrammos otakii, skin mucus, intestine, high-throughput sequencing technology, microbial diversity

摘要： 大泷六线鱼(Hexagrammos otakii)是一种具有代表性的高价值冷水性鱼类。通过分析大泷六线鱼表皮粘液及肠道内容物微生物菌群特征，了解其微生物多样性及所携带的自身特有的潜在病原微生物情况。采集设施化车间养殖的大泷六线鱼，提取表皮粘液和肠道内容物基因组DNA，通过16S rRNA高通量测序技术和生物学分析方法，对不同样本的V3+V4区基因文库进行分析。结果表明，大泷六线鱼表皮粘液和肠道内容物样本拥有共同的OTUs为33个，且Venn图呈现了不同来源样本之间的相似性和差异性。Rank-abundance曲线显示了不同样本的均匀度和丰富度，测序数据合理、可信。Alpha指数平均值显示肠道内容物微生物丰富度较高，而表皮粘液微生物多样性较高；Beta多样性显示了不同来源样本间的异质性及同一来源样本间的相似性。从门水平上看，优势菌门均为蓝菌门（Cyanobacteria）、变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）；而属水平结果不同，肠道内容物样本中优势菌属包括Streptophyta、芽孢杆菌属（Bacillus）、杆菌属（Bacillaceae_unclassified）、气单胞菌属（Aeromonas）及弧菌属（Vibrio），表皮粘液样本中优势菌属包括Streptophyta、气单胞菌属（Aeromonas）、杆菌属（Bacillaceae_unclassified）、香味菌属（Myriudes）、假单胞菌属（Gemmobacter）及弧菌属（Vibrio）。Heatmap热图结果提示，不同微生物菌群结构发挥出不同生物学功能，其中未分类杆菌属、气单胞菌属、弧菌属、假单胞菌属等条件性致病菌的存在均可能导致病害的发生。因此，揭示表皮粘液和肠道内容物样本中微生物的多样性及主要病原菌属的特征对大泷六线鱼健康养殖和疾病防控具有一定的指导意义。

关键词: 大泷六线鱼, 表皮粘液, 肠道, 高通量测序, 微生物多样性