Low pH (LpH) poses a significant challenge to the health, immune response, and growth of aquatic animals worldwide. Crayfish () is a globally farmed freshwater species with a remarkable adaptability to various environmental stressors. However, the effects of LpH stress on the microbiota and host metabolism in crayfish intestines remain poorly understood. In this study, integrated analyses of antioxidant enzyme activity, histopathological damage, 16S rRNA gene sequencing, and liquid chromatography-mass spectrometry (LC-MS) were performed to investigate the physiology, histopathology, microbiota, and metabolite changes in crayfish intestines exposed to LpH treatment. The results showed that LpH stress induced obvious changes in superoxide dismutase and catalase activities and histopathological alterations in crayfish intestines. Furthermore, 16S rRNA gene sequencing analysis revealed that exposure to LpH caused significant alterations in the diversity and composition of the crayfish intestinal microbiota at the phylum and genus levels. At the genus level, 14 genera including , and , exhibited significant differences in their relative abundances. The LC-MS analysis revealed 859 differentially expressed metabolites in crayfish intestines in response to LpH, including 363 and 496 upregulated and downregulated metabolites, respectively. These identified metabolites exhibited significant enrichment in 24 Kyoto Encyclopedia of Genes and Genomes pathways ( < 0.05), including seven and 17 upregulated and downregulated pathways, respectively. These pathways are mainly associated with energy and amino acid metabolism. Correlation analysis revealed a strong correlation between the metabolites and intestinal microbiota of crayfish during LpH treatment. These findings suggest that LpH may induce significant oxidative stress, intestinal tissue damage, disruption of intestinal microbiota homeostasis, and alterations in the metabolism in crayfish. These findings provide valuable insights into how the microbial and metabolic processes of crayfish intestines respond to LpH stress.

中文翻译：

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综合微生物组和代谢组分析揭示了低 pH 对小龙虾（克氏原螯虾）肠道健康和体内平衡的影响

低 pH (LpH) 对全世界水生动物的健康、免疫反应和生长构成重大挑战。小龙虾 () 是一种全球养殖的淡水物种，对各种环境压力具有卓越的适应能力。然而，LpH 胁迫对小龙虾肠道微生物群和宿主代谢的影响仍知之甚少。本研究通过抗氧化酶活性、组织病理学损伤、16S rRNA基因测序和液相色谱-质谱（LC-MS）等综合分析，研究LpH环境下小龙虾肠道的生理、组织病理学、微生物群和代谢物变化。治疗。结果表明，LpH胁迫引起小龙虾肠道超氧化物歧化酶和过氧化氢酶活性的明显变化以及组织病理学改变。此外，16S rRNA基因测序分析表明，暴露于LpH会导致小龙虾肠道微生物群在门和属水平上的多样性和组成发生显着改变。在属水平上，包括 、 和 在内的 14 个属的相对丰度存在显着差异。 LC-MS分析显示小龙虾肠道中响应LpH的差异表达的代谢物有859个，其中分别有363个和496个上调和下调的代谢物。这些鉴定的代谢物在 24 个京都基因和基因组百科全书途径中表现出显着富集（<0.05），分别包括 7 个和 17 个上调和下调途径。这些途径主要与能量和氨基酸代谢有关。相关分析显示，LpH 处理期间小龙虾的代谢物与肠道微生物群之间存在很强的相关性。这些发现表明，LpH 可能会引起显着的氧化应激、肠道组织损伤、肠道微生物群稳态破坏以及小龙虾代谢的改变。这些发现为了解小龙虾肠道的微生物和代谢过程如何响应 LpH 应激提供了宝贵的见解。