Top Institute Food and Nutrition (TIFN), Nieuwe Kanaal 9A, 6709 PA Wageningen, The Netherlands.
Int J Food Microbiol. 2011 Jan 5;144(3):421-31. doi: 10.1016/j.ijfoodmicro.2010.10.029. Epub 2010 Oct 29.
We investigated the formation of single and mixed species biofilms of Listeria monocytogenes strains EGD-e and LR-991, with Lactobacillus plantarum WCFS1 as secondary species, and their resistance to the disinfectants benzalkonium chloride and peracetic acid. Modulation of growth, biofilm formation, and biofilm composition was achieved by addition of manganese sulfate and/or glucose to the BHI medium. Composition analyses of the mixed species biofilms using plate counts and fluorescence microscopy with dual fluorophores showed that mixed species biofilms were formed in BHI (total count, 8-9 log₁₀ cfu/well) and that they contained 1-2 log₁₀ cfu/well more L. monocytogenes than L. plantarum cells. Addition of manganese sulfate resulted in equal numbers of both species (total count, 8 log₁₀ cfu/well) in the mixed species biofilm, while manganese sulfate in combination with glucose, resulted in 1-2 log₁₀ more L. plantarum than L. monocytogenes cells (total count, 9 log₁₀ cfu/well). Corresponding single species biofilms of L. monocytogenes and L. plantarum contained up to 9 log₁₀ cfu/well. Subsequent disinfection treatments showed mixed species biofilms to be more resistant to treatments with the selected disinfectants. In BHI with additional manganese sulfate, both L. monocytogenes strains and L. plantarum grown in the mixed species biofilm showed less than 2 log₁₀ cfu/well inactivation after exposure for 15 min to 100 μg/ml benzalkonium chloride, while single species biofilms of both L. monocytogenes strains showed 4.5 log₁₀ cfu/well inactivation and single species biofilms of L. plantarum showed 3.3 log₁₀ cfu/well inactivation. Our results indicate that L. monocytogenes and L. plantarum mixed species biofilms can be more resistant to disinfection treatments than single species biofilms.
我们研究了单核细胞增生李斯特菌 EGD-e 和 LR-991 菌株与植物乳杆菌 WCFS1 作为次要物种的单种和混合物种生物膜的形成，以及它们对季铵盐和过氧乙酸消毒剂的抗性。通过在 BHI 培养基中添加硫酸锰和/或葡萄糖来调节生长、生物膜形成和生物膜组成。使用平板计数和双荧光染料荧光显微镜对混合物种生物膜进行的成分分析表明，在 BHI 中形成了混合物种生物膜（总计数为 8-9 log₁₀ cfu/孔），并且它们包含比植物乳杆菌细胞多 1-2 log₁₀ cfu/孔的单核细胞增生李斯特菌。添加硫酸锰导致混合物种生物膜中两种物种的数量相等（总计数为 8 log₁₀ cfu/孔），而硫酸锰与葡萄糖联合使用导致植物乳杆菌比单核细胞增生李斯特菌细胞多 1-2 log₁₀（总计数为 9 log₁₀ cfu/孔）。相应的单核细胞增生李斯特菌和植物乳杆菌单种生物膜中含有多达 9 log₁₀ cfu/孔。随后的消毒处理表明，混合物种生物膜对所选消毒剂的处理更具抗性。在添加硫酸锰的 BHI 中，暴露于 100 μg/ml 季铵盐 15 分钟后，两种单核细胞增生李斯特菌菌株和在混合物种生物膜中生长的植物乳杆菌的活菌数均少于 2 log₁₀ cfu/孔，而两种单核细胞增生李斯特菌菌株的单种生物膜的活菌数减少了 4.5 log₁₀ cfu/孔，植物乳杆菌的单种生物膜的活菌数减少了 3.3 log₁₀ cfu/孔。我们的结果表明，与单种生物膜相比，单核细胞增生李斯特菌和植物乳杆菌混合物种生物膜对消毒处理的抵抗力可能更强。
