Mixed species biofilms of Listeria monocytogenes and Lactobacillus plantarum show enhanced resistance to benzalkonium chloride and peracetic acid

S. van der Veen, T. Abee

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130 Citations (Scopus)

Abstract

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. Research Highlights ¿Listeria monocytogenes and Lactobacillus plantarum form mixed species biofilms. ¿Single species biofilms are more resistant than planktonic cells. ¿Mixed species biofilms are more resistance than single species biofilms. Keywords: Biofilm; Listeria monocytogenes; Lactobacillus plantarum; Peracetic acid; Benzalkonium chloride
Original languageEnglish
Pages (from-to)421-431
JournalInternational Journal of Food Microbiology
Volume144
Issue number3
DOIs
Publication statusPublished - 2011

Keywords

  • food-processing environment
  • stress resistance
  • sos response
  • egd-e
  • strains
  • growth
  • sanitizers
  • microorganisms
  • disinfectants
  • contamination

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