Inhibitory effects of piperine and black pepper essential oil on multispecies biofilm formation by Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa

This study aimed to evaluate the antimicrobial and antibiofilm activities of black pepper essential oil (BPEO) and piperine and the effect of piperine on gene expression in a multispecies biofilm composed of Listeria monocytogenes, Salmonella Typhimurium, and Pseudomonas aeruginosa on a polypropylene surface. The minimal inhibitory concentrations of BPEO and piperine were 100 and 25 mg/mL, respectively, against this consortium of microorganisms. Sessile cell counts were 5.35–7.35 log CFU/cm2 and varied over time. The total population eradicated in the biofilm ranged from 78.9% (5.88 log CFU/cm2) to 99.8% (4.16 log CFU/cm2). Evaluation of biofilm-related gene expression showed upregulation of the L. monocytogenes genes agrC (24 and 72 h), agrD (72 h), and prfA (72 h) and downregulation of all evaluated S. Typhimurium and P. aeruginosa genes (24 and 72 h) in the untreated control biofilm. The addition of piperine resulted in upregulation of the L. monocytogenes genes agrB (24 and 72 h), agrC (72 h), agrD (24 and 72 h), and prfA (24 h); the S. Typhimurium genes agfA (24 and 72 h), adrA (24 and 72 h), and csgD (72 h); and all evaluated P. aeruginosa genes (24 and 72 h). Piperine more effectively controlled the multispecies biofilm.