Proteomics Analysis Of The Interaction Mechanism Between Lactobacillus Plantarum And Saccharomyces Cerevisiae In Sourdough

Sourdough was a mixture of flour and water.It was a mixed fermentation system composed of lactic acid bacteria(LAB),yeast,mold and other bacteria.Among them,Lactobacillus plantarum and Saccharomyces cerevisiae were the dominant strains,which had an important influence on the flavor,structure and nutritional quality of fermented products.Compared with the single culture sourdough,co-cultivation sourdough had better flavor and quality.This thesis systematically explored L.plantarum Sx3 and S.cerevisiae Sq7 isolated from traditional sourdough.The main research contents and results were as follows:In this thesis,the colony number,p H and TTA of Sx3 and Sq7 in single culture and co-cultivation sourdough were first explored.In the early stage of fermentation,the cell growth trend in the co-cultivation sourdough was lower than that of single culture sourdough,probably because Sx3 and Sq7 were in the process of adapting to the new environment during the initial fermentation process,resulting in the slow growth of Sx3 and Sq7.High-throughput sequencing of microbial diversity proved that Sx3 and Sq7 were the dominant strains in sourdough,ensuring that the experimental strains had no pollution and denaturation during the experiment,which provided guarantee for the subsequent development of proteomics.Through proteomics analysis,it can be seen that the interaction mechanism of Sx3 and Sq7 mainly focuses on carbohydrate metabolism,amino acid metabolism,energy metabolism,translation,folding,sorting and degradation.Compared with Sq7 single culture sourdough,the up-regulated of L-lactic acid dehydrogenase in co-cultivation sourdough promoted the formation of lactic acid,which can increase the flavor of sourdough,extend the shelf life,and increase the acidity and refresh taste.The up-regulated of pyruvate decarboxylase promoted the production of acetic acid,which was considered to be an important enhancer of flavor compounds.The increased of fumaric acid content can increase the acidity of sourdough taste,and had an important effect on bacteriostatic.Increased sucrose content can increase the sweetness of sourdough.Seryl-t RNA synthetase was up-regulated,which improved protein stability during fermentation and had a significant effect on specific types of proteins.The inhibition of citrate synthase activity slowed the catalytic condensation reaction of oxaloacetate and acetyl-Co A,thereby inhibiting the production of succinic acid and malic acid downstream of citric acid.The interaction of L.plantarum Sx3 and S.cerevisiae Sq7 lead to a decrease in the content of tyrosine,serine,glycine,alanine and aspartic acid.This experiment provided a theoretical basis for the in-depth study of the interaction mechanism of LAB and yeast,and laid the foundation for the development of functional sourdough.