PDF(Pubmed)
Abstract：
Listeria monocytogenes is recognized as one of the primary pathogens responsible for foodborne illnesses. The ability of L. monocytogenes to form biofilms notably increases its resistance to antibiotics such as ampicillin and tetracycline, making it exceedingly difficult to eradicate. Residual bacteria within the processing environment can contaminate food products, thereby posing a significant risk to public health. In this study, we used crystal violet staining to assess the biofilm-forming capacity of seven L. monocytogenes strains and identified ATCC 19112 as the strain with the most potent biofilm-forming. Subsequent fluorescence microscopy observations revealed that the biofilm-forming capacity was markedly enhanced after two days of culture. Then, we investigated into the factors contributing to biofilm formation and demonstrated that strains with more robust extracellular polymer secretion and self-agglutination capabilities exhibited a more pronounced ability to form biofilms. No significant correlation was found between surface hydrophobicity and biofilm formation capability. In addition, we found that after biofilm formation, the adhesion and invasion of cells were enhanced and drug resistance increased. Therefore, we hypothesized that the formation of biofilm makes L. monocytogenes more virulent and more difficult to remove by antibiotics. Lastly, utilizing RT-PCR, we detected the expression levels of genes associated with biofilm formation, including those involved in quorum sensing (QS), flagellar synthesis, and extracellular polymer production. These genes were significantly upregulated after biofilm formation. These findings underscore the critical relationship between extracellular polymers, self-agglutination abilities, and biofilm formation. In conclusion, the establishment of biofilms not only enhances L. monocytogenes\' capacity for cell invasion and adhesion but also significantly increases its resistance to drugs, presenting a substantial threat to food safety.
摘要：
单核细胞增生李斯特菌被认为是导致食源性疾病的主要病原体之一。单核细胞增生李斯特菌形成生物膜的能力显著增加了其对抗生素如氨苄西林和四环素的抗性,很难根除。加工环境中残留的细菌会污染食品，从而对公众健康构成重大风险。在这项研究中,我们使用结晶紫染色来评估7个单核细胞增生李斯特菌菌株的生物膜形成能力,并鉴定出ATCC19112为生物膜形成能力最强的菌株。随后的荧光显微镜观察表明，培养两天后，生物膜形成能力显着增强。然后，我们调查了导致生物膜形成的因素，并证明具有更强大的细胞外聚合物分泌和自我凝集能力的菌株表现出更明显的形成生物膜的能力。在表面疏水性和生物膜形成能力之间没有发现显着相关性。此外,我们发现生物膜形成后，细胞的粘附和侵袭增强，耐药性增加。因此,我们假设生物膜的形成使单核细胞增生李斯特菌更具毒性，更难以被抗生素去除。最后,利用RT-PCR，我们检测到与生物膜形成相关的基因的表达水平，包括参与群体感应(QS)的人，鞭毛合成，和细胞外聚合物的生产。这些基因在生物膜形成后显著上调。这些发现强调了细胞外聚合物之间的关键关系，自我凝集能力，和生物膜的形成。总之,生物膜的建立不仅增强了单核细胞增生李斯特菌的细胞侵袭和粘附能力，而且显著增加了其对药物的抗性，对食品安全构成重大威胁。
