外界因素和食品内部环境变化对Brevilaterin抗菌特性的影响

为探讨Brevibacillus laterosporus产的抗菌肽Brevilaterin的抗菌特性,考察了不同外界因素对其抗菌活性的影响,重点研究了食品内部环境变化与其抗菌作用的关系。研究结果表明:Brevilaterin的抗菌活性几乎不受所选金属离子、乳化剂(除大豆磷脂外)、增稠剂、酶、高浓度蔗糖和反复冻融处理的影响,稳定性良好。随着食品内部温度、pH值和渗透压的改变,Brevilaterin对受试菌S.aureus、L.monocytogenes、M.luteus、P.aeruginosa、L.lactis和H.alkalicola的抗菌作用规律均发生显著变化,主要变化为:相比于受试菌生长最适温度(37℃)时的作用效果,4℃下Brevilaterin对M.luteus的最小抑菌浓度(MIC)和最小杀菌浓度(MBC)均降至1/8,10℃下Brevilaterin对P.aeruginosa、L.monocytogenes和S.aureus的MIC和MBC均降至1/4~1/2。相比于菌株生长最适pH值(6~7)时的作用效果,pH值为2时,Brevilaterin对L.lactis的MIC和MBC均降至1/2;pH值为8~9时,Brevilaterin对S.aureus的MIC和MBC均降至1/2;同样,pH值为7时,Brevilaterin对H.alkalicola的MIC和MBC均降至pH值为11(最适pH)时的1/4。相比于常压时的作用效果,高渗条件下Brevilaterin对S.aureus的MIC和MBC值均降至1/2。因此,当食源性致病菌的生长条件偏离其最适条件时,Brevilaterin能表现出更强的抗菌作用,而此时的MIC和MBC均可降至最适条件下的1/8~1/2。Brevilaterin不仅能稳定发挥其抗菌作用,而且能随着食品内部环境的变化表现出不同的规律,这可为其未来在食品防腐中的应用提供更科学的指导。

Effect of External Factors and Internal Environment Changes of Food on Antibacterial Properties of Brevilaterin

In order to study the antibacterial properties of antibacterial peptide Brevilaterin secreted by Brevibacillus laterosporus,effect of different external factors of food on its antibacterial activity were investigated,and its MIC and MBC values in varied internal environment of food were further checked.The results showed that Brevilaterin exhibited good stability towards those selected metal ions,emulsifiers(except soybean phospholipid),thickeners,enzymes,high concentration of sugar and repeated treatment of freeze-thaw.Furthermore,MIC and MBC values of Brevilaterin against S.aureus,L.monocytogenes,M.luteus,P.aeruginosa,L.lactis and H.alkalicola could be significantly changed with variation of the temperature,pH and osmotic pressure of food.Compared with the effect at the optimal temperature(37℃)of those foodborne pathogens mentioned above,the MIC and MBC values of Brevilaterin on M.luteus decreased to 1/8 at 4℃,the MIC and MBC values of Brevilaterin on P.aeruginosa,L.monocytogenes and S.aureus were decreased to 1/4~1/2 at 10℃.Compared with the effect when strains were grown at the optimum pH(6~7),the MIC and MBC of Brevilaterin on L.lactis were reduced to 1/2 at pH 2,and the MIC and MBC of Brevilaterin on S.aureus were reduced to 1/2 at pH 8~9.Similarly,the MIC and MBC of Brevilaterin for H.kalicola at pH 7 were reduced to 1/4 of that at pH 11(optimal pH).The MIC and MBC of Brevilaterin for S.aureus under hypertonic condition were reduced to 1/2 of that under normal pressure.Therefore,when the growth conditions of foodborne pathogens deviated from their optimal conditions,Brevilaterin showed stronger antibacterial effects,while both of MIC and MBC values were reduced to 1/8~1/2 of that at optimal conditions.All of these properties exhibited by Brevilaterin indicated its scientific guideline on the food application in the future.