Antimicrobial effects of sanitizers against planktonic and sessile Listeria monocytogenes cells according to the growth phase

Abstract

This study was designed to investigate the individual or combined effects of sanitizers on survival of planktonic or sessile Listeria monocytogenes cells at different phase of growth. The sanitizers tested included: (i) acetic acid (pH 5.0), (ii) NaOH (pH 12.0), (iii) 10% Na2SO4, (iv) 10% Na2SO4 and acetic acid (pH 5.0), (v) 10% Na2SO4 and NaOH (pH 12.0), (vi) a quaternary ammonium (20 ppm) and (vii) glyceryl monolaurate (75 ppm). Results revealed a great efficacy of alkaline treatments on both sessile and planktonic cells with a slightly higher resistance of 6 h biofilms. Quaternary ammonium appeared very effective in killing more than 98% of cells, but a resistance of 7 days biofilm was observed. Other sanitizers did not succeed in inhibiting totally the pathogen but acted in a similar way on both sessile and planktonic cells. Renewing the medium or not do not seem to be the major cause of a resistance emergence.

Listeria monocytogenes EGD-e Biofilms: No Mushrooms but a Network of Knitted Chains

“…Our observations of the biofilm under static conditions showed unorganized 3D structures that were similar to those observed previously (3,12,13). In contrast, for the biofilm under flow conditions we described another organization of L. monocytogenes EGD-e biofilms that consisted of a network of knitted chains that could structure the microcolonies.…”

“…The literature related to the biofilm structures of L. monocytogenes deals with, in most cases, static experiments using SEM (3,12,13,28,32,39,49). LSCM is a powerful in situ visualization tool for the temporal study of the 3D structures of biofilms (27,29,30,45,55,58) and has been used to study the biofilm structure of a variety of microorganisms, such as Pseudomonas aeruginosa and S. aureus (26,29).…”

“…For instance, plate counting has been used to quantify sessile cells of L. monocytogenes on abiotic surfaces (1, 5-7, 10, 12, 13, 32, 43, 47, 52, 53). Also, biofilms of L. monocytogenes have been quantified by using the microplate adhesion method (3,11,23,33,48), while their structures have been investigated by scanning electron microscopy (SEM) (3,12,13,28,32,39,49), epifluorescence microscopy (9,24,28,36,37,41,46), or laser-scanning confocal microscopy (LSCM) (10,31,51). LSCM has allowed the visualization of fully hydrated samples and has revealed the elaborate 3D structure of biofilms (14).…”

Effect of peracetic acid on biofilms formed by Listeria monocytogenes strains isolated from a Brazilian cheese processing plant

“…Biofilms of Listeria have been shown to be much more resistant to stress and to sanitizing agents than planktonic cells (Chavant, Gaillard-Martine, Hebraud, 2004). It is believed that biofilm formation enhances the capacity of foodborne bacteria to survive stressors that are commonly found in the food-processing environment (e.g.…”

Cell envelope constituents of Pseudomonas putida contributing to growth and survival in low-water-content habitats

“…Phenotypic differences between biofilm and planktonic cells have been reported based on protein expression Sauer et al, 2002) and resistance to toxic compounds, such as antimicrobials (Desai et al, 1998;Brooun et al, 2000;Spoering and Lewis, 2001;Chavant et al, 2004), reactive oxygen intermediates (ROI) Hassett et al, 1999) and heavy metals (Teitzel and Parsek, 2003;Harrison et al, 2004). To our knowledge this is the first report describing greater tolerance of biofilm than planktonic cells to a physical environmental stressor.…”