单增李斯特菌（LM）是重要的食源性致病菌，其菌膜形成机理尚未阐明。磷酸转移酶系统（PTS）对细菌的生长代谢和菌膜形成具有重要调控作用。前期研究发现，活性氧组分（ROS）诱导剂甲基紫精（MV）可明显抑制LM菌膜的形成，并且细胞内ROS升高可导致PTS组分MpoB表达量明显下降。为探明MpoB在MV抑制LM菌膜形成中的作用与机理，本项目首先构建mpoB基因缺失突变株和回复突变株，在有/无MV作用下分析该基因对氧胁迫抗性、菌膜形成能力及相关生物特性的影响；其次，利用iTRAQ串联质谱技术，比较MV作用下野生型和突变株菌膜细胞内蛋白的表达差异；然后，借助生物信息学手段对差异蛋白进行GO注释与KEGG通路聚类；随后，通过实时荧光定量PCR技术对关键蛋白的差异表达进行mRNA水平的验证；最后，综合上述表型特征变化与关键差异蛋白所在通路，阐释MpoB在MV抑制LM菌膜形成中的作用与机理。

Listeria monocytogenes is one of the important foodborne pathogens that can form biofilm. The mechanism of biofilm formation of the pathogen is not yet clear. Phosphotransferase system (PTS) plays an important role in regulating bacterial growth metabolism and biofilm formation. Our previous studies demonstrated that methyl violet (MV) could significantly inhibit the biofilm formation of L. monocytogenes, and the increased activities of reactive oxygen species (ROS) in cell resulted in the decreased expression level of PTS-MpoB. This project aims to explore the effect and the mechanism of MpoB in MV inhibiting the biofilm formation of L. monocytogenes. First, mpoB deletion mutant and reverse mutant are constructed to analyze the effect of mpoB deletion on oxygen stress resistance, biofilm formation ability and biofilm related physiological properties with/without MV. Second, iTRAQ is used to compare differentially expressed protein profiles of biofilm cells between the wild type and mpoB deletion mutant with MV. Then, the differential expressed proteins are functionally annotated by GO and clustered by KEGG pathway by means of bioinformatics methods. Subsequently, the differential expressions of key proteins are confirmed by RT-qPCR. Lastly, the effect and mechanism of PTS-MpoB in MV inhibiting biofilm formation of L. monocytogenes are elucidated based on the phenotypic changes combined with the pathways containing key differential proteins.