Biofilms isolated from washing machines from three continents and their tolerance to a standard detergent.
The goal of this comparative study was to investigate biofilm forming microorganisms living in washing machines (WMs). Biofilms were sampled from 11 washing machines from four countries and three continents. Among the 94 isolated strains, 30% were potential human pathogens. Representative strains were selected and biofilm formation was evaluated with the crystal violet (CV) assay. The majority of the WM isolates formed more biofilm than their reference strains. Biofilms of P. putida WM (the largest biofilm producer) were exposed to different concentrations (0.0007-7 g l(-1)) of the standard detergent IEC-A* at 30°C for 30 min and observed with confocal laser scanning microscopy. Using quantitative CVA, P. putida WM biofilm removal required higher detergent concentrations than the type strain. However, for both strains the recommended detergent concentration (7 g l(-1)) was insufficient to completely clean surfaces from cell debris and exopolymeric substances.
Empa, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Biomaterials, Lerchenfeldstrasse 5, CH-9014 St. Gallen, Switzerland.
Jasmin
J
Gattlen
Caroline
C
Amberg
Manfred
M
Zinn
Laurie
L
Mauclaire
D018441:Biofilms / Q000187:drug effects*; D057219:Biofouling; D003902:Detergents / Q000494:pharmacology*; D004203:Disinfection / Q000379:methods*; D005658:Fungi / Q000502:physiology; D005840:Gentian Violet; D006794:Household Articles; D016958:Pseudomonas putida / Q000187:drug effects* / Q000302:isolation & purification / Q000502:physiology
D003902:Detergents; D005840:Gentian Violet