Rice-shrimp culture: a better intestinal microbiota, immune enzymatic activities, and muscle relish of crayfish (Procambarus clarkii) in Sichuan Province.

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.