Ⅱa类乳酸菌抗菌肽Lac-B23的结构及其对牛乳中嗜冷菌的抑制机理研究

Psychrophiles spoilage could reduce milk safety and quality seriously. It is the essential method to inhibit the growth of psychrophiles by food preservatives. Due to the potential safety hazard of the chemical preservatives, it is significant to develop bio-preservative.ClassⅡa bacteriocin Lac-B23 produced from lactobacillus J-23 has been investigated to appear anti-psychrophiles activity, and the production regulation model and purification of Lac-B23 has been established in our previous study. Based on these, taking Lac-B23 purified in our lab as object, the diversity of ClassⅡa bacteriocin will be revealed. Taking ClassⅡa bacteriocin Lac-B23 as control, the structure identification will be conducted by using CD, MALDI-TOF MS, NMR and other technology. The structure-activity relationship and activity sites of Lac-B23 will be studied by enzymatic hydrolysis technology.Taking P. fluorescens as indicator, by using of SEM, qRT-PCR, fluorescence analysis, and bioinformatics methods, the antimicrobial mechanism of Lac-B23 to psychrophiles will be investigated from the level of cell and genetic. The purpose of this program is to provide a theoretical basis for the effective prevention and control of psychrophiles in raw milk.

嗜冷菌对原料乳污染严重影响乳制品品质。利用食品防腐剂控制嗜冷菌生长是避免其危害的有效方法。目前以化学防腐剂为主，存在安全隐患，发掘能抑制嗜冷菌的生物防腐剂具有重要意义。本课题组前期筛选到对嗜冷菌有明显抑制作用的乳杆菌Lactobacillus-J23，确定其抗菌成分为Ⅱa类抗菌肽Lac-B23；结题的青年基金完成了Lac-B23合成调控及分离纯化研究。在此基础上，本项目以纯化的Lac-B23为研究对象，利用IR、CD、MALDI-TOF-MS等技术剖析Lac-B23结构；采用酶水解技术，基于水解片段活性和结构，确定Lac-B23活性部位；以典型嗜冷菌-荧光假单胞菌为指示菌，以细胞表面特性和Man-PTS系统为研究对象，联合SEM/TEM、qRT-PCR、紫外/荧光光谱技术以及生物信息学手段，从细胞水平和分子水平探讨Lac-B23对嗜冷菌抑菌机制。本项目旨在为牛乳中嗜冷菌的控制提供理论支撑。

嗜冷菌对原料乳污染严重影响乳制品品质。利用食品防腐剂控制嗜冷菌生长是避免其危害 的有效方法。目前以化学防腐剂为主，存在安全隐患，发掘能抑制嗜冷菌的生物防腐剂具有重 要意义。本课题组前期筛选到对嗜冷菌有明显抑制作用的乳杆菌，确定其抗菌成分为Ⅱa类抗菌肽Lac-B23。 在此基础上，本项目以纯化的Lac-B23为研究对象，利用IR、CD、MALDI-TOF-MS等技术剖析Lac-B23结构；采用酶水解技术，基于水解片段活性和结构，确定Lac-B23活性部位；以典型嗜冷 菌-荧光假单胞菌为指示菌，以细胞表面特性和Man-PTS系统为研究对象，联合SEM/TEM、qRT-PCR、紫外/荧光光谱技术以及生物信息学手段，从细胞水平和分子水平探讨Lac-B23对嗜冷菌抑菌机制。本项目按计划完成了研究目标。研究完成了乳酸菌抗菌肽Lac-B23的理化性质，同时完成了产Lac-B23乳酸菌菌株的全基因组测序；联合化学手段和生物信息学方法确定了抗菌肽Lac-B23结构，从细胞水平和分子水平探讨了抗菌肽Lac-B23对典型嗜冷菌-荧光假单胞菌的抑菌机理，并进一步研究了确定了抗菌肽Lac-B23对荧光假单胞菌生物膜的消减作用，拓宽了其应用范围。本项目为将来原料乳及其他食品中的嗜冷菌危害控制提供了技术支撑。