Investigation of the selective bactericidal effect of several decontaminating solutions on bacterial biofilms including useful, spoilage and/or pathogenic bacteria Original Research Article

The aim of this work was to investigate the selective bactericidal effect of several decontaminating solutions on some spoilage, pathogenic and useful bacteria isolated from a traditional meat workshop. Fourteen decontaminating solutions, i.e., acid, alkaline, osmotic, biocide solutions or their combinations were tested on five bacterial species grown as monospecies biofilms. The solution made of monolaurin (0.075% w/v) and acetic acid at pH 5.4 was the most selective decontaminating solution. It reduced by only 0.2 and 0.4 log Lactobacillus spp. and Staphylococcus carnosus, whereas Pseudomonas fluorescens, Pseudomonas putida and Listeria monocytogenes exhibited reductions of 3.7, 3.2 and 4.2 log, respectively. The acetic solution (pH 5.4) and the solution containing monolaurin (0.075% w/v) and sodium sulfate (12% w/v) were also selective. But their bactericidal effects on Pseudomonas species were relatively small. Four selected solutions were then applied to seven bacterial species grown as multispecies biofilms. The mixture solution of monolaurin (0.075% w/v) and acetic acid at pH 5.4 showed again the best selectivity. Finally, lowering the pH of the acetic solution from 5.4 to 5.2 increased the selective decontamination.