Inhibitory Effect of Mexican Oregano (Lippia berlandieri Schauer) Essential Oil on Pseudomonas spp. Biofilm Formation

Introduction: Biofilms are defined as adherent, matrix-enclosed bacterial populations. In nature, microorganisms usually attach to solid surfaces, especially at the liquid–solid interface. In general, biofilms are very resistant to some physical treatments, and are considered a potential hazard and a source of bacterial contamination of foods. An alternative of this is the search for natural compounds, like essential oils (EO’s), with antimicrobial properties, which could be used in the biofilm formation.

Purpose: The aim of this study was to evaluate the inhibitory effect of Mexican oregano (Lippia berlandieri Schauer) EO on Pseudomonas spp. biofilm formation.

Methods: Pseudomonas spp. minimal inhibitory concentration (MIC) was determined with EO concentrations of 0 to 2000 ppm. Biofilm formation in stainless steel surfaces was evaluated with growth curves using concentrations below the MIC values. Gompertz equation parameters were used to describe biofilm formation.

Results: Mexican oregano EO MIC value was 1600 ppm whereas biofilm formation in stainless steel surface is affected at lower MIC values (800 ppm of EO) and inhibitory film formation at this concentration is immediately. Gompertz model adequately described the biofilm formation growth curves. Significant differences (P < 0.05) between the Gompertz parameters was observed among essential oil concentration, increasing the lag phase, decreasing maximum growth and growth rate as EO concentration increased.

Significance: Mexican oregano EO could inhibit the development of Pseudomonas spp. biofilm formation on stainless steel surfaces and could be an alternative for cleaning these kinds of surfaces and equipment.