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.

The effects of ferulic and salicylic acids on Bacillus cereus and Pseudomonas fluorescens single- and dual-species biofilms

“…Adhesion is a complex process that is affected by many aspects, such as the physicochemical characteristics of bacteria, the material surface properties, and the environmental factors (An and Friedman, 1998;Machado et al, 2011). Moreover, it is known that cell surface properties (e.g., hydrophobicity and surface charge) are relevant to the process of bacterial adhesion and biofilm formation (Simões et al, 2008(Simões et al, , 2010a. When there is contact with the sub-stratum, bacterial adhesion can be mediated by hydrophobic inter-actions.…”

“…The free energy of adhesion between the bacterial cells and PS surfaces was assessed according to Simões et al (2008). When studying the interaction (free energy of adhesion -∆ between surface i (bacterium) and I (PS) that immersed or dissolved in water, the total interaction energy, ∆ , can be expressed as:…”

The effects of surface type on the removal of Bacillus cereus and Pseudomonas fluorescens single and dual species biofilms

“…The free energy of adhesion between the bacterial cells and PMMA and SS surfaces was assessed according to Simões et al (2008a). When studying the interaction free energy of adhesion -G TOT between surface i (bacterium) and I (PMMA or SS) that are immersed or dissolved in water, the total interaction energy, ∆ , can be expressed as:…”

The effects of surface properties on Escherichia coli adhesion are modulated by shear stress

“…A volume of 60 mL from this culture was centrifuged (for 10 min at 3202 g) and the cells were washed twice with citrate buffer 0.05 M [24], pH 5.0. The pellet was then resuspended and diluted in the same buffer to obtain a cell concentration of 7.6x10 7 cell.mL -1 .…”