Comparison Of Environmental Factors And Muscle Quality In Rice-shrimp Integrated Culture System In Different Areas And Establishment Of Geographica Origin Traceability System

Procambarus Clarkii,commonly known as crayfish,is one of the important economic shrimp in freshwater,with fast growth rate,wide feeding range,strongly adaptability and reproductive ability.The cultivation methods mainly include paddy field cultivation,pond cultivation and lotus pond cultivation.Paddy field cultivation is the main production methods.Crayfish culture in paddy fields is mainly distributed in Jiangsu Province,Hubei Province and other places.In south of China,it has short winter and long summer period with large rice planting area,which should be suitable for the growth and reproduction of crayfish.However,the farming scale of crayfish in south of China is small and the production is low.Beyond that,the quality of crayfish of South China has a certain gap compared with Hubei Province and other places.In this study,we compared the water quality,soil physical and chemical factors,microbial community structure,muscle quality and food composition of crayfish between South China and the main breeding area of P.clarkii,and traced the origin of P.clarkii by combining mineral elements and stable isotopes.The results are as follows:1.Analysis of microbial community structure in rice-shrimp integrated culture system of three different areasTo study the environment of the integrated rice-shrimp farming system in different regions and the bacterial community structure differences in the gut of P.clarkii,to provide a basis for improving the integrated farming strategies of rice and shrimp in different regions.Using Illumina Miseq high-throughput sequencing technology,the microbial community structures in the intestines of P.clarkii,culture water and sediments from Hubei,Hunan and Guangdong groups were compared,and the correlation between bacterial structure and environmental factors was analyzed.The results showed that the richness of the microbial community in the integrated rice and shrimp breeding system of the Hubei group was higher than that of the Hunan and Guangdong groups.The dominant bacterial phyla in the water body in the integrated rice and shrimp breeding system in different regions were Actinobacteria,Cyanobacteria,Proteobacteria and Bacteroidetes;Proteobacteria was the dominant bacterial phylum in the sediment.Proteobacteria,Bacteroidetes and Firmicutes were the dominant phyla in the intestinal tract of P.clarkii in Hubei group;the dominant bacterial genera were Citrobacter（10.85%）,Aeromonas（9.88%）and[Anaerorhabdus]＿furcosa＿groqup（8.43%）and so on.The predominant phyla in the intestine of P.clarkii in the Hunan group were Firmicutes and Actinobacteria;the predominant genera were ZOR0006（9.78%）,Bacteroides（5.41%）and[Anaerorhabdus]＿furcosa＿group（3.98%）.The predominant phyla in the gut of P.clarkii from the Guangdong group were Firmicutes and Proteobacteria;the predominant genera were Citrobacter（9.31%）,Bacteroides（4.29%）and[Anaerorhabdus]＿furcosa＿group（4.58%）and so on.The results of environmental factor correlation analysis showed that total suspended particulates（TSS）and total phosphorus（TP）had significant effects on bacterial community structure in water,while phosphate(PO₄^3--P)and chemical oxygen demand(COD_Cr)had significant effects on gut microbial structure.Studies have shown that there are certain differences in the intestinal microbes of water bodies,sediments and P.clarkii,in different regions,and the microbial structures of water bodies and sediments are more similar.The microbial diversity of the water body in the integrated rice and shrimp breeding system of the Hubei group is the highest,which is beneficial to the stable breeding system.The species of dominant phyla in culture systems in different regions did not change,but the relative abundance of dominant phyla and genera changed.The nutrient content in the culture environment will have a certain degree of influence on the microbial community structure.2.Comparative analysis of food composition and nutrition relationship of rice and shrimp integrated culture system in different areasIn order to compare the food web structure and feeding habits of P.clarkii from different regions of China,theδ¹³C andδ¹⁵N values of food sources and consumers in Guangdong group,Hunan group and Hubei group were analyzed,and the contribution rates of different feed to the diet of P.clarkii were calculated.The results showed that theδ¹³C values of consumers ranged from-30.43‰to-21.82‰,δ¹⁵N values ranged from3.04‰to 7.16‰,and nutrient levels ranged from 1 to 3.71.The nutritional grade of P.clarkii in Hubei group（2.86）was lower than that in Guangdong group（3.03）and Hunan group（3.52）.The comparison of food web structure showed that the range of nitrogen value is 4.8 in Hubei group,5.85 in Hunan group and 3.99 in Guangdong group,indicating that the nutrient level length of rice and shrimp integrated culture system is different in different areas,among which Hubei group was the longest.The range of carbon value of Hubei group is 6.28,that of Hunan group is 7.28,and that of Guangdong group is 8.99.The range of carbon value of rice and shrimp integrated culture system of Guangdong group was larger,indicating that the range of consumers’initial food source is wider and the degree of niche diversity is higher.According to the analysis of food composition,the contribution rate of rice stalk to crayfish food in Hunan group was significantly higher than that in Guangdong group and Hubei group.3.Comparison of muscle quality and metabolic enzyme activity of Procambarus clarkii cultured in different areas paddy fields from different areasBy comparing the differences of metabolic enzyme activity,muscle nutrient composition of P.clarkii cultured in different areas of paddy fields and the muscle quality of P.clarkii was evaluated in order to provide a basis for reasonable guidance of rice field culture in South China.In this study,crayfish from Wuhan of Hubei province,Yongzhou of Hunan province and Shaoguan of Guangdong province were used to determine the contents of nutritional components and fatty acids in the tail muscle of Procambarus clarkii,evaluate its nutritional value,and detect the activities of physiological metabolic enzymes in hepatopancreas and intestines.The results showed that crude ash and crude protein in muscle of Hubei and Hunan groups were significantly higher than those of Guangdong group（P<0.05）,water content was significantly lower than that in Guangdong group（P<0.05）,and the contents of total amino acids,essential amino acid and flavor amino acids were higher than those of Guangdong group（P<0.05）.The hepatopancreas superoxide dismutase activity of crayfish in Hubei group was significantly higher than that in Guangdong group（P<0.05）,but the activities of catalase,alkaline phosphatase,acid phosphatase and malondialdehyde were significantly lower than those of Guangdong group（P<0.05）.In a word,the P.clarkii in Hubei group has higher antioxidant activity and muscle nutritive value compare to those in Guangdong group after farming in paddy fields,which met the dietary needs of human body and was a high-quality protein source.4.Geographical origin traceability of Procambarus clarkii based on stable isotopes and mineral elementsIn order to explore the application prospect of mineral elements and stable isotopes in the origin tracing of P.clarkii,the origin tracing system of P.clarkii was established.Determine the contents of fourteen mineral elements（Na,Mg,Al,K,Ca,Mn,Zn,Cu,Fe,Sr,Ba,As,Se and Cd）and the abundances of C and N stable isotopes in the muscle tissue of P.clarkii from Hubei group,and Hunan group and Guangdong group.By using multivariate statistical analysis,we established a discriminant model for distinguishing the three geographical origins from each other.The results of one-way Anova and Duncan multiple comparison showed that elements Na,K,Sr,Ba,Cu,Mn,Fe,As,Al andδ¹³C andδ¹⁵N had significant differences among the three regions（P<0.05）,but Mg had no significant differences among different regions（P>0.05）.The discriminant accuracy of linear discriminant analysis for samples from Guangdong group,Hunan group and Hubei group was 95%,95%and 100%,respectively.The initial overall discriminant accuracy was 96.7%,and the cross-validation discriminant accuracy was 93.3%.Principal component analysis finally screened out three main components,the cumulative variance contribution rate of 78.77%,A three-dimensional coordinate system was established by using principal components to draw scatter diagrams of samples from three regions in the coordinate system.Samples from three regions were distributed in three different regions in the coordinate system.The results showed that the combination of mineral elements and stable isotopes could distinguish P.clarkii from different areas.