title: Co-culture with Listeria monocytogenes within a dual-species biofilm community strongly increases resistance of Pseudomonas putida to benzalkonium chloride.
abstract: Biofilm formation is a phenomenon occurring almost wherever microorganisms and surfaces exist in close proximity. This study aimed to evaluate the possible influence of bacterial interactions on the ability of Listeria monocytogenes and Pseudomonas putida to develop a dual-species biofilm community on stainless steel (SS), as well as on the subsequent resistance of their sessile cells to benzalkonium chloride (BC) used in inadequate (sub-lethal) concentration (50 ppm). The possible progressive adaptability of mixed-culture biofilms to BC was also investigated. To accomplish these, 3 strains per species were left to develop mixed-culture biofilms on SS coupons, incubated in daily renewable growth medium for a total period of 10 days, under either mono- or dual-species conditions. Each day, biofilm cells were exposed to disinfection treatment. Results revealed that the simultaneous presence of L. monocytogenes strongly increased the resistance of P. putida biofilm cells to BC, while culture conditions (mono-/dual-species) did not seem to significantly influence the resistance of L. monocytogenes biofilm cells. BC mainly killed L. monocytogenes cells when this was applied against the dual-species sessile community during the whole incubation period, despite the fact that from the 2nd day this community was mainly composed (>90%) of P. putida cells. No obvious adaptation to BC was observed in either L. monocytogenes or P. putida biofilm cells. Pulsed field gel electrophoresis (PFGE) analysis showed that the different strains behaved differently with regard to biofilm formation and antimicrobial resistance. Such knowledge on the physiological behavior of mixed-culture biofilms could provide the information necessary to control their formation.
authors.affiliation: Department of Food Science and Nutrition, University of the Aegean, Myrina, Lemnos island, Greece.
authors.forename: Efstathios
authors.initials: E
authors.lastname: Giaouris
authors.forename: Nikos
authors.initials: N
authors.lastname: Chorianopoulos
authors.forename: Agapi
authors.initials: A
authors.lastname: Doulgeraki
authors.forename: George-John
authors.initials: GJ
authors.lastname: Nychas
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology*; D001422:Bacterial Adhesion; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018920:Coculture Techniques; D024881:Drug Resistance, Bacterial; D006801:Humans; D008089:Listeria monocytogenes / Q000187:drug effects / Q000502:physiology*; D008088:Listeriosis / Q000382:microbiology; D011552:Pseudomonas Infections / Q000382:microbiology; D016958:Pseudomonas putida / Q000187:drug effects* / Q000502:physiology*; D013193:Stainless Steel / Q000032:analysis
chemical_list: D000891:Anti-Infective Agents, Local; D001548:Benzalkonium Compounds; D013193:Stainless Steel