Listeria monocytogenes can form long-lasting biofilms on food-contact surfaces. Lactic acid bacteria (LAB) have shown promise in antagonizing this microorganism in liquid media. However, the ecological relationships differ when cells are forming biofilms. In this work, we propose the use of Lactobacillus biofilms as surface “conditioners” to modulate the adhesion of L. monocytogenes. For this, the biofilm formation ability of Lactobacillus fermentum MP26 and Lactobacillus salivarius MP14 (human milk origin), fluorescently labeled by transfer of the mCherry-encoding pRCR12 plasmid, was first evaluated. Then, mature biofilms of these strains transformed with pRCR12 for expressing the fluorescent protein mCherry were used as adhesion substrate for GFP-tagged L. monocytogenes Scott A. The resulting biofilms were studied in terms of cellular population and attached biomass (cells plus matrix). Species distribution inside the biofilm structure was revealed by confocal laser scanning microscopy (CLSM). Although none of the Lactobacillus spp. strains reduced the adhesion of L. monocytogenes Scott A, species interactions seem to interfere with the synthesis of extracellular polymeric substances and species distribution inside the biofilms. In dual-species biofilms, CLSM images revealed that Lactobacillus cells were trapping those of L. monocytogenes Scott A. When surfaces were conditioned with Lactobacillus biofilms, the spatial distribution of L. monocytogenes Scott A cells was species-specific, suggesting these interactions are governing the ultimate biofilm structure. The results here obtained open new possibilities for controlling L. monocytogenes dispersal using these Lactobacillus spp. biofilms as a “natural” immobilization way. Whether species interactions could modify the virulence of L. monocytogenes still remains unclear.

单核细胞增生李斯特菌可在与食物接触的表面上形成持久的生物膜。乳酸菌（LAB）在对抗液体培养基中的这种微生物方面已显示出希望。但是，当细胞形成生物膜时，生态关系不同。在这项工作中，我们建议使用乳杆菌生物膜作为表面“调节剂”来调节单核细胞增生李斯特菌的粘附。为此，发酵乳杆菌MP26和唾液乳杆菌的生物膜形成能力。首先评估通过编码mCherry的pRCR12质粒进行荧光标记的MP14（人乳来源）。然后，将这些用pRCR12转化的表达荧光蛋白mCherry的菌株的成熟生物膜用作带有GFP标签的单核细胞增生李斯特菌Scott A的粘附底物。对所得生物膜进行了细胞数量和附着生物量（细胞加基质）的研究。通过共聚焦激光扫描显微镜（CLSM）揭示了生物膜结构内部的物种分布。虽然没有乳酸杆菌属。菌株减少了单核细胞增生李斯特菌的粘附Scott A，物种间的相互作用似乎会干扰细胞外聚合物的合成以及生物膜内部的物种分布。在双物种的生物膜，CLSM图像显示，乳杆菌细胞俘获那些的李斯特菌斯科特A.当表面用空调乳杆菌生物膜，空间分布单增李斯特菌斯科特A细胞是物种特异性的，这表明这些相互作用支配最终的生物膜结构。此处的结果为使用这些乳杆菌控制单核细胞增生李斯特氏菌的扩散提供了新的可能性。spp。生物膜是一种“天然”的固定方法。物种之间的相互作用是否可以改变单核细胞增生李斯特菌的毒力仍不清楚。