Study On Stability And Function Evaluation Of Antibacterial Peptides Derived From Goat Casein

The enzymatic hydrolysis of casein peptides has a good stability and a high security, andcan inhibit a variety of bacteria, thus, it has a wide range of applications. Goat milk is veryimportant in China, casein accounts for75%goat milk, which the most content is β-casein.Goat’s casein can obtained antimicrobial peptide with enzymolysis, but the stability, thefunctional evaluation and the further applied research of goat’s casein antibacterial peptidehas not been reported. Using goat’s casein as raw material with enzymatic hydrolysis toproduce antibacterial peptides, increase the source of antibacterial peptide, improve theirshelf life by adding peptide in raw milk, inhibit virus as a chemical inhibitor, and provide atheoretical basis for development and large industrial application of the goat’s caseinantibacterial peptide.According to the shortage situation of goat’s casein antibacterial peptide and application,the goat’s casein with papain enzymolysis obtained antibacterial peptide, throughbacteriostatic test of the agar dilution method on Escherichia coli, Staphylococcus aureus,Salmonella, Shigella, Lester and Sakazaki to measure their inhibitory effect of bacteria; usingthe bacteria inhibition zone on Escherichia coli, Staphylococcus aureus, and Salmonellathreeas index to explore the effect of light, heat, and pH stability on antibacterial peptides; usingthe pH value and the total number of colonies as index to explore its effect of antimicrobialpeptide on milk shelf-life at25℃and4℃. By determining the Africa green monkey kidneycells (Vero) and bovine kidney cells (MDBK) about the maximum non-toxic dose, cytopathiceffect (CPE), index of blood coagulation value, virus content to explore peptide inhibit onavian influenza virus(AIV) and type-I bovine herpes virus (BHV-1), and lay a goodfoundation of food, medicine and cosmetics industriation.The results are as follows:(1) the test of antibacterial peptide with bacteriostatic ring as a result on Escherichia coli,Staphylococcus aureus, Salmonella, Shigella, Lester bacteria and Enterobacter sakazakiithese6kinds of pathogen showed that the antibacterial peptide has the certain inhibition onthese6kinds of pathogenic bacteria. (2) After using heat and light processing, antibacterial peptide has not significant in theEscherichia coli, Staphylococcus aureus and Salmonella this three kinds of bacteriainhibition zone; the effects of pH on antibacterial peptide is also no significant on inhibitionzone under neutral and alkaline conditions, but the inhibition zone is disappear on the strongacidic conditions. It showed that the peptide is stable in heat, light, neutral and alkalineconditions, but it will flocculating in strong acidic conditions.(3) The results of antibacterial peptide on the preservation of raw milk show that, at25℃, the control group reached the total number of colony105cfu/g in22h, while samplesreached index in28h with adding antibacterial peptide, and antimicrobial peptides canprolong the preservation time of6h compared with the control group; at4℃,the controlgroup reached the index in the33days, but antibacterial peptides samples reached the index in41days, and antimicrobial peptides can prolong the preservation time of8ays.(4)The maximum non-toxic dose of antibacterial peptide on Vero cells and MDBK cellsis25μg/mL, using different concentrations of antimicrobial peptides to deal with AIV andBHV-1, it showed typical CPE with sensitive cells. Experiments show that the antibacterialpeptide has a great toxicity on cell, and it has not obvious effect on the AIV (RNA virus) andBHV-1(DNA virus) with on the cell non-toxic dose range.