PolyAT Base Double-stranded DNA Enhances The Antibacterial Activity Of Histones

Food-borne diseases are caused by food-borne pathogenic microorganisms which do great harm to consumers' health.Therefore,this kind of food safety issues have attracted worldwide attention.As the most common pathogenic microorganism of food-borne pathogenic bacteria,such as Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)that are widely distributed in nature,which are easy to contaminate food and cause food poisoning.Histones,as a basic structural component of eukaryotic chromatin,it can be extracted from many eukaryotes.Because of its richness in arginine and lysine,it can be easily combined with DNA to improve the antimicrobial activity of histone by synthesizing histone-DNA complex.So the current research will be conducted to check whether the histone-DNA can improve the antimicrobial activity of histone or not.The main research content and results can be summarized into the following two aspects:1.In this study,using Gram-negative E.coli as the tested strain,the minimum bactericidal concentration(MBC)and the minimum inhibitory concentration(MIC)of histone against E.coli were tested.The MBC was 0.5 ?g/mL and the MIC was 0.5 mg/mL.The effects of different concentrations of DNA on the antibacterial activity of histone were investigated.The results showed that when the concentration of DNA was 0.01 ?M,DNA has the best bactericidal enhancement effect on histone.We also investigated the effects of DNA double strands with the same and different length and the same base composition on the bactericidal properties of histones.The results showed that the most significant was when the bactericidal characteristics of DNA double chain is(AT)10.Finally,the concentration of histone was optimized.When the concentration of histone was 100 ?g/mL,the bactericidal effect of histone-DNA complex was the best.The results of the optimization experiment showed that the bactericidal rate of single histone is about 30%,and that of histone-DNA complex is 100%.2.In this study,using Gram-positive S.aureus as the tested strain,the antibacterial and antibacterial activity of histones against S.aureus was investigated,and the MBC was 20 ?g/mL.The MIC was 2 mg/mL.The bactericidal effect of DNA on histone was consistent with that of E.coli,and the bactericidal characteristics of histone were most obviously affected by DNA when DNA double strand was(AT)10,the concentration of histone was 0.01 ?M,and the concentration of histone was 100 ?g/mL.The final experimental results showed that the bactericidal rate of single histone is about 35%,the bactericidal rate of histone-DNA complex can reach 75%.The results showed that DNA could improve the antibacterial activity of histone,the reason of which is that DNA enhanced the hydrophobicity of histone,which made it easier to contact with the surface of bacteria and improve its antibacterial activity.By comparison of the two bacteria strain,we concluded that the bactericidal activity of histone-DNA complex against E.coli was particularly significant,presumably due to the different cell wall composition between Gram-positive bacteria and Gram-negative bacteria.