Department of Food and Experimental Nutrition, Faculty of Pharmaceutical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 580 B.14, 05508-900, São Paulo, SP, Brazil.
Food Research Center (FoRC), Faculty of Pharmaceutical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 580 B.14, 05508-900, São Paulo, SP, Brazil.
World J Microbiol Biotechnol. 2018 Apr 12;34(4):61. doi: 10.1007/s11274-018-2445-4.
Listeria monocytogenes is a Gram-positive bacterium commonly associated with foodborne diseases. Due its ability to survive under adverse environmental conditions and to form biofilm, this bacterium is a major concern for the food industry, since it can compromise sanitation procedures and increase the risk of post-processing contamination. Little is known about the interaction between L. monocytogenes and Gram-negative bacteria on biofilm formation. Thus, in order to evaluate this interaction, Escherichia coli and L. monocytogenes were tested for their ability to form biofilms together or in monoculture. We also aimed to evaluate the ability of L. monocytogenes 1/2a and its isogenic mutant strain (ΔprfA ΔsigB) to form biofilm in the presence of E. coli. We assessed the importance of the virulence regulators, PrfA and σ, in this process since they are involved in many aspects of L. monocytogenes pathogenicity. Biofilm formation was assessed using stainless steel AISI 304 #4 slides immersed into brain heart infusion broth, reconstituted powder milk and E. coli preconditioned medium at 25 °C. Our results indicated that a higher amount of biofilm was formed by the wild type strain of L. monocytogenes than by its isogenic mutant, indicating that prfA and sigB are important for biofilm development, especially maturation under our experimental conditions. The presence of E. coli or its metabolites in preconditioned medium did not influence biofilm formation by L. monocytogenes. Our results confirm the possibility of concomitant biofilm formation by L. monocytogenes and E. coli, two bacteria of major significance in the food industry.
李斯特菌是一种革兰氏阳性细菌，通常与食源性疾病有关。由于其能够在不利的环境条件下生存并形成生物膜，因此该细菌是食品工业的主要关注点，因为它会破坏卫生程序并增加后处理污染的风险。关于李斯特菌与生物膜形成中的革兰氏阴性细菌之间的相互作用知之甚少。因此，为了评估这种相互作用，我们测试了大肠杆菌和李斯特菌单独或共同形成生物膜的能力。我们还旨在评估李斯特菌 1/2a 及其同源缺失突变株（ΔprfA ΔsigB）在存在大肠杆菌的情况下形成生物膜的能力。我们评估了毒力调节因子 PrfA 和 σ 在该过程中的重要性，因为它们涉及李斯特菌致病性的许多方面。使用浸入脑心浸液肉汤、再水合奶粉和大肠杆菌预培养培养基中的不锈钢 AISI 304 #4 载玻片来评估生物膜形成。我们的结果表明，野生型李斯特菌形成的生物膜量高于其同源缺失突变株，这表明 prfA 和 sigB 对生物膜的形成很重要，特别是在我们的实验条件下的成熟过程。大肠杆菌或其代谢物在预培养培养基中的存在并不影响李斯特菌的生物膜形成。我们的结果证实了李斯特菌和大肠杆菌这两种在食品工业中具有重要意义的细菌同时形成生物膜的可能性。
