Intestinal microbiota play an important role in the intestinal immunity and nutrient absorption, even muscle nutritional components, and the composition and function were affected by environment. In this study, the intestinal microbiota and immune enzyme, nutritional flavor of muscle of crayfish in rice field, and pond cultivation model were compared in summer and autumn. The results of Shannon diversity and Chao 1 index of intestinal microbiota based on 16S sequencing analysis showed that the diversity and abundance in autumn were higher than in summer. And the diversity and abundance of intestinal microbiota of different model in the same season were different. Four dominant phyla (relative abundance > 5% at least in one sample) of the intestinal microbiota were Bacteroidetes, Firmicutes, Proteobacteria, and Tenericutes. From summer to autumn, the intestinal immune enzyme activity of crayfish in both models showed a decreasing trend. In summer, the activity of catalase and alkaline phosphatase of crayfish cultured in the pond was significantly higher than that in rice field (P < 0.05). In autumn, the activity of catalase and lysozyme of crayfish cultured in rice field was significantly higher than that in pond (P < 0.05). The contents of umami and sweetish amino acids of muscle were higher in rice field than in pond, and the percentage of glutamic acid and alanine was significantly higher in rice field than in pond (P < 0.05). Thus, rice field model can make crayfish a more stable intestinal environment and a better intestinal immune enzyme activity and muscular flavor. Key points • The intestinal microbiota of crayfish in rice field had tended to stabilize from summer to autumn. • The crayfish had better nutrient absorption and stronger immune abilities in the rice field. • The crayfish cultured in rice field had higher overall umami concentration than in pond.

中文翻译：

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稻虾养殖：四川省的小龙虾（Procambarus clarkii）具有更好的肠道菌群，免疫酶活性和肌肉风味。

肠道菌群在肠道免疫和营养吸收，甚至肌肉营养成分中起着重要作用，其组成和功能受环境的影响。本研究比较了夏，秋两季稻田小龙虾的肠道菌群和免疫酶，肌肉营养风味以及池塘养殖模式。基于16S测序分析的肠道菌群香农多样性和Chao 1指数表明，秋季的多样性和丰度高于夏季。同一季节不同模型肠道菌群的多样性和丰度也不同。肠道菌群的四个优势门（至少一个样本中的相对丰度> 5％）是拟杆菌，硬毛菌，变形杆菌和Tenericutes。从夏天到秋天 两种模型中小龙虾的肠道免疫酶活性均呈下降趋势。夏季，池塘养殖小龙虾的过氧化氢酶和碱性磷酸酶活性明显高于稻田（P <0.05）。秋季，稻田中养殖的小龙虾的过氧化氢酶和溶菌酶活性显着高于池塘（P <0.05）。稻田中肌肉的鲜味含量和甜味氨基酸含量高于池塘，谷田中谷氨酸和丙氨酸的含量显着高于池塘（P <0.05）。因此，稻田模型可以使小龙虾具有更稳定的肠道环境，并具有更好的肠道免疫酶活性和肌肉风味。要点•稻田小龙虾的肠道菌群从夏季到秋季都趋于稳定。•小龙虾在稻田中具有更好的营养吸收和较强的免疫能力。•稻田养殖的小龙虾的鲜味总浓度高于池塘。