Biofilms isolated from washing machines from three continents and their tolerance to a standard detergent

Abstract

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.

Characterization of Microbial Communities in Household Washing Machines

“…The study of Gattlen et al [8] also found gram-negative Proteobacteria being the predominant phylum inside the washing machine as well. This is also in line with the fact that bacterial biofilms of environmental samples are dominated by Proteobacteria [32 -36].…”

“…Previous studies could show that organisms that were isolated from biofilms from washing machines are more tolerant to chemical detergents compared to control strains [8,15]. For this reason potential drug-resistant organisms, which have been identified in the domestic environment, imply a potential health risk due to cross-contaminations during the washing process.…”

“…For example in dishwashers [5], in showerheads [6] or on household surfaces [7] biofilms have been found and opportunistic pathogens were identified. Washing machines have been proven to be an ideal habitat for microbial communities as well [8]. A humid environment and the supply of nutrients provide perfect living conditions for microorganism in washing machines.…”

“…Until now microorganisms have been identified to be responsible for malodour in laundry [12,13] and few microorganisms have been isolated and identified to be characteristic for biofilms from washing machines [8]. It is a fact that the characteristics of washing procedures changed to low temperatures and detergents without bleaching agent are preferred [14].…”

Laundry Performance: Effect of Detergent and Additives on Consumer Satisfaction

“…The development of malodours in the washing machine is due to the biofilm growth [31], an inconvenience that can be The stain required the use of additional specific stain removal products 29.7…”