title: The effects of a biocide and a surfactant on the detachment of Pseudomonas fluorescens from glass surfaces.
abstract: Application of antimicrobial chemicals is a general procedure in the cleaning and disinfection of food-contacting surfaces. Adhesion to glass surfaces and chemically induced detachment of Pseudomonas fluorescens ATCC 13525(T) were studied in situ, under flow conditions, in a well-controlled parallel plate flow chamber (PPFC). Ortho-phthalaldehyde (OPA) and cetyltrimethyl ammonium bromide (CTAB) were applied separately, at several concentrations, to attached bacteria and their subsequent detachment was monitored. Following treatments the remaining adhered bacteria were characterized in terms of viability and cell size. Simultaneously, the planktonic cell surface was characterized in order to correlate PPFC results with thermodynamic approaches for adhesion evaluation, and surface free energy of chemically treated cells with adhesion strength. About 2.8x10(6) cells/cm(2) adhered to the glass surface after 30 min of bacterial flow, although thermodynamic analyses evidenced unfavourable adhesion. The independent application of OPA and CTAB promoted bacterial detachment to a small extent (16% of total cells). The remaining adhering bacteria were totally non-viable for OPA> or =0.75 mM and CTAB> or =0.25 mM, showing a lack of correlation between bacterial viability and detachment. The cellular size decreased as attachment proceeded and with chemical treatment. Both chemicals altered the cell surface properties, increasing the cell-glass adhesion strength, and promoting the emergence of polar characteristics. The overall results emphasize that OPA and CTAB were markedly ineffective in removing glass-attached P. fluorescens, demonstrating that bacteria can be non-viable but remain strongly attached to the adhesion surface.
authors.affiliation: Centro de Engenharia Biológica, Universidade do Minho, 4710-057 Braga, Portugal. mjvsimoes@deb.uminho.pt
authors.forename: Manuel
authors.initials: M
authors.lastname: Simões
authors.forename: Lúcia C
authors.initials: LC
authors.lastname: Simões
authors.forename: Sara
authors.initials: S
authors.lastname: Cleto
authors.forename: Maria O
authors.initials: MO
authors.lastname: Pereira
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Vieira
mesh_terms: D001422:Bacterial Adhesion / Q000187:drug effects*; D018441:Biofilms / Q000254:growth & development; D002593:Cetrimonium Compounds / Q000494:pharmacology; D015169:Colony Count, Microbial; D046169:Dermoscopy; D004202:Disinfectants / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005898:Glass; D011551:Pseudomonas fluorescens / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology; D013501:Surface-Active Agents / Q000494:pharmacology*; D014872:Water Movements; D009764:o-Phthalaldehyde / Q000494:pharmacology
chemical_list: D002593:Cetrimonium Compounds; D004202:Disinfectants; D013501:Surface-Active Agents; D009764:o-Phthalaldehyde