Correlation Analysis Of Microbial Metabolites Change And Microflora Succession For Chilled Meat Of Tan Sheep

Microbial metabolites play a pivotal role on water retention, tenderness, color and other physicochemical index of the chilled meat surface of Tan sheep during storage. In this study, microbial metabolites on the chilled meat surface of Tan sheep were detected systematically using metabolomics techniques in order to determine the differential metabolites and find out the relevance between these metabolites and microbial community succession. The results will provide a theoretical reference for the technological innovation in production and marketing of chilled meat of Tan sheep, build a foundation for the molecular ecology theory in the chilled meat preservation, and offer some ideas for the development of computer simulation systems for the microbial community succession in chilled meat.1. Taking the microbes on the chilled meat surface of Tan sheep as subject and the peak intensity or peak number in GC-MS as standards, the preparation method for microbial metabolomics sample of the chilled meat of Tan sheep was studied. The optimum condition was established as the quenching time of liquid nitrogen 1 min, low temperature centrifugation after meat thawing for 3 min in -9℃ by 12000 rpm to separate the cells. Intracellular metabolites were extracted by methanol-chloroform method in 3 min, and the derivatization treatment was performed at 70℃.2. According to the established sample preparation method, the different compounds were determined by GC-MS using intracellular sugar, fat, protein and other metabolites as the detected targets. The obtained data were standardized and analyzed by multivariate analysis using SIMCA software. The results showed that 30 species of differential metabolites which the similarity values were greater than 700 were determined in different storage periods. Among them,30 species of differential metabolites accurately matched with the metabolic pathways, and the metabolic pathways of 5 species were not found out in KEGG database possibly due to that the information of these metabolites were not included in the metabolic pathways database. These 5 metabolites respectively were acetanilide, 2-Hydroxyvaleric acid, trans-4-hydro-xy-L-proline, taurine and 1,5-Anhydroglucitol.3. Using the selective culture method, the initial phases on the chilled meat surface of Tan sheep in Yanchi, Ningxia were determined as Pseudomonas, Enterobacter, Lactobacillus and Brchothrix thermosphacta, and the dominant bacteria was Pseudomonas followed by Enterobacter. The results of principal component analysis and cluster analysis showed that it had greater relevance between Pseudomonas and D-glyceric acid and phenylalanine. The relevance between glucose-1-phosphate, Inosine-5’-monophosphate and Lactobacillus was significant. Meanwhile, aspartic acid, asparagine, ribose and acetanilide had great interrelation with Enterobacter and Brchothrix thermosphacta.