Purification And Characteirzation Of Barley Immune Protein

Barley is the main raw material for brewing, barley anti-bacterial protein （peptide） on therole of Saccharomyces cerevisiae has been the people’s concern, previous studies showed thatsome of these antimicrobial proteins are heat-resistant peptide, small molecules with heatstability, which can withstand boiling temperatures, such as them can tolerate the temperatureof boiling wort in the fermentation process of beer. These protein impact on yeast growth andmetabolism in the process of fermentation, affecting their normal growth and fermentation,resulting in the extension of beer fermentation cycle, yeast hypoglycemic slow. In this paper,we improved the anti-bacterial protein extraction rate; analyzed the antibacterial proteincontent of several typical domestic and external barley, detected their anti-yeast properties;separated and purified nsltp protein, and detected its anti-yeast properties. This researchmakes a guideline for the practical production of beer in the beer production process.In this study, the Australian Barley （Hordeum sp. Gairdner） as the research object, usingdilute sulfuric acid extraction, ammonium sulfate fractionation, precision-exclusion dialysisbags of dialysis, response surface method, improved barley anti-bacterial crude proteinextraction methods, simpled the extraction step and improved the extraction rate ofantibacterial proteins.The raw material in this research was the eight kinds of domestic and foreign barley.From the research that was about crude protein barley extraction, protein content, theantibacterial activity of crude protein, and its thermal stability analysis. Study found thatdomestic Danpi-2has the highest content of anti-bacterial crude protein, up to338μg·g^-1.When the content of crude protein in medium was32μg·mL^-1, the yeast growth was inhibited,inhibition rate reached50%after12h culture.In this research, the nsltp in the crude protein was purified using DEAE cellulose column,G-50dextran column, CM-glucan-C50column chromatography, using SDS-PAGE electro-phoresis showed a single band, indicating a pure electrophoretic separation has been reached,the molecular weight of nsltp was16KDa.The anti-yeast activity of nsltp was detected, whennsltp content in the fermentation broth reaches100μg·mL^-1, the yeast growth inhibition rate reached50%.