Studies On Nutritional Quality,metabolome And Gut Microbiome Of Chinese Mitten Crab(Eriocheir Sinensis) From Different Growth Environment

Chinese mitten crab(Eriocheir sinensis),is one of the major domesticated crab in China.It mainly habits in pond,lake and river,with great environmental differences.The aim of this study was to explore the effects of growing environment nutritional quality,differential metabolites and gut microbiome of Chinese mitten crab.Nutrient quality,growth,metabolome and gut microbiome of Chinese mitten crab,which habits in pond,lake and the Yangtze River,were studied by means of molecular biology and morphology.The results are as follows:1.Analysis of nutritional components and quality of Chinese mitten crab from different habits.In this study,the differences in indicators related to growth,as well as the differences in nutritional components,fatty acids,mineral elements and amino acids in muscle tissue of the adult Chinese mitten crab,habits in pond,lake and Yangtze River were analyzed.The results showed the hepatopancreas index(HSI),gonadosomatic index(GSI)and meat yield(MY)of lake crab were the highest,while the moisture content,crude fat and ash contents were the lowest.Pond crab had the highest content of condition factor(CF),crude ash and mineral content.The contents of crude protein,non-essential amino acid(NEAA)and essential amino acid(EAA)were the highest in the Yangtze River crab.The total contents of saturated fatty acids(SFA),monounsaturated fatty acids(MUFA)and polyunsaturated fatty acids(PUFA)of lake crab were higher than those of pond crab and Yangtze River crab.The results showed that the amino acid content of Yangtze River crab was the highest;the fatty acid content of lake crab was the highest;the pond crab had advantages in plumpness index and mineral elements.2.Metabolome analysis of Chinese mitten crab from different habits.In this study,liquid chromatography-mass spectrometry(LC-MS)was used to detect and analyze the differences of metabolome in muscle tissue of Chinese mitten crab under three growing habits.The results show that a total of 631 annotated metabolites were detected in the muscle tissues of Chinese mitten crab under three growing habits,among which lipids accounted for 32.05% and peptides accounted for19.23%,lipid metabolism and amino acid metabolism are the pathways with the most annotated metabolites.PLS-DA diagram showed that there were obvious differences in the metabolites of Chinese mitten crab under the three growing habits.A total of 144 differential metabolites were identified,among which 110 were upregulated and 34 were downregulated in the pond crab compared with the Yangtze River crab.For the lake crab,146 differential metabolites were identified,among which 123 were upregulated and 23 were downregulated compared with the Yangtze River crab.A total of 132 metabolites were identified in the pond crab,among which 54 were upregulated and 78 were downregulated compared with the lake crab.There were obvious differences of metabolites in the three growing habits.The relative abundance of citrate and creatine metabolites in the Yangtze River crab was relatively higher,the abundance of vitamin B2 and geniposide acid in the metabolites of pond crab was higher,the abundance of 13(s)-Hpode and DHA in lake crab was higher.The difference of metabolites in Chinese mitten crab is closely related to its growing habits,which indicates that the metabolic difference of Chinese mitten crab is greatly affected by its growing habits.3.Analysis of gut microbiome of Chinese mitten crab from different growth habits.A total of 1,433,338 sequences were obtained after sequencing the 32 samples from the three habits,and 850 different OTUs representing 359 genera were identified.The alpha diversity of the Chao index indicated the significant differences in community richness between pond and lake crabs and between pond and river crab.By contrast,the alpha diversity of the Shannon index indicated no significant differences in community diversity among the groups.The beta diversity analysis through PCo A indicated a significant divergence among the three groups.Although Proteobacteria,Bacteroidetes,Tenericutes,and Firmicutes were dominant bacteria phyla in the three environmental groups,a divergent gut microbiome was observed among the three groups.the relative abundances of Proteobacteria and Bacteroidetes were the highest in the Yangtze River crab and lake crab,respectively.the abundances of Tenericutes,Actinobacteria,and Patescibacteria were highest in the pond crab.The core flora of gut microbiome of the Chinese mitten crab was the same in the three growing habits,but the composition and species of the microbial community of the Chinese mitten crab were different,and there was unique gut microbiome in different growing habits.