Gut microbes influence the growth and health of hosts and are affected by various host traits, including genotype, nutrition condition and the surrounding environment. Haemorrhagic septicaemia is one of the most common diseases in fish species, including the endangered species Chinese sturgeon (Acipenser sinensis). Here, we investigated the changes in the complexity, composition and function of the gut microbiota of cultured Chinese sturgeon with haemorrhagic septicaemia using 16S rRNA sequencing. Although Firmicutes, Fusobacteria, Proteobacteria and Bacteroidetes constituted the most abundant phyla, we still detected substantial variations in community structure under haemorrhagic septicaemia, especially with an abnormally low abundance of Clostridium, Aeromonas, Ralstonia and some enzyme-producing microbes. We also found significantly decreased (p < 0.01) alpha diversity (ACE and Chao indices) in diseased fish. More importantly, these changes in the microbial structure were closely related to the function of amino acid biosynthesis, starch and sucrose metabolism, and amino sugar and nucleotide sugar metabolism. Our findings provide significant insights into the correlation between gut microbiota and the occurrence of haemorrhagic septicaemia, which might be useful for the early diagnosis, prevention and treatment of haemorrhagic septicaemia in cultured Chinese sturgeon via controlling the gut microbes.

中文翻译：

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患有出血性败血症的中华鲟（Acipenser sinensis）肠道微生物群的变化

肠道微生物影响宿主的生长和健康，并受各种宿主特征的影响，包括基因型、营养状况和周围环境。出血性败血症是鱼类最常见的疾病之一，包括濒临灭绝的中华鲟（Acipenser sinensis）。在这里，我们使用 16S rRNA 测序研究了培养的出血性败血症中华鲟肠道微生物群的复杂性、组成和功能的变化。尽管厚壁菌门、梭菌门、变形菌门和拟杆菌门构成了最丰富的门，但我们仍然检测到出血性败血症下群落结构的显着变化，尤其是梭菌、气单胞菌的丰度异常低, Ralstonia和一些产酶微生物。我们还发现患病鱼的 alpha 多样性（ACE 和 Chao 指数）显着降低（p < 0.01）。更重要的是，微生物结构的这些变化与氨基酸生物合成、淀粉和蔗糖代谢以及氨基糖和核苷酸糖代谢的功能密切相关。我们的研究结果为肠道微生物群与出血性败血症发生之间的相关性提供了重要见解，这可能有助于通过控制肠道微生物对养殖中华鲟出血性败血症进行早期诊断、预防和治疗。