Effect of carvacrol and thymol on Salmonella spp. biofilms on polypropylene

The present study evaluated the effects of carvacrol and thymol against Salmonella spp. biofilm on polypropylene. The efficacy of the compounds was assessed by quantifying Salmonella spp. cells during and after biofilm formation on polypropylene and performing scanning electron microscopy. During biofilm formation, carvacrol and thymol, at subinhibitory concentrations, reduced bacterial counts about 1-2 log, while established Salmonella spp. biofilms were reduced about 1-5 log by carvacrol and thymol, at MIC or 29 MIC. The greatest reduction in carvacrol-treated biofilms, about 5 log, was observed with 156 and 312 mu g mL(-1) (MIC and 29 MIC) in established Salmonella Typhimurium ATCC 14028 biofilms. Thymol showed the greatest reduction, about 4 log, at 624 mu g mL(-1) (29 MIC) against mature Salmonella Enteritidis biofilm. Carvacrol and thymol reduced the number of Salmonella spp. cells on polypropylene, suggesting their potential for the control of Salmonella spp. biofilms.