ANTIFUNGAL ACTIVITY OF THYMOL ON PLANKTONIC AND BIOFILM CELLS

Abstract

The purpose of this study was to evaluate the antifungal effects of thymol on fungi planktonic and biofilm cells. Firstly, the antifungal activity of a thymol-based product on reducing fungi load in poultry drinking water samples was assessed in vitro using the plate count method. Samples were treated by increasing concentrations of thymol (1, 2 and 4 g.l^-1 of product). Reduction is about one log unit for 1 g.l^-1, about two log units for 2 g.l¹, and a total desperation for 4 g.l^-1. Secondly, the antifungal activity was tested on biofilms formed on coiled pipes using an experimental arrangement simulating animals watering conditions in poultry farming. Two concentrations (1 and 2 g.l^-1) were used in two ways, preventive and curative treatment. The first one consisted in preventing fungal development on pipes and the biofilm formation. The second consisted in treating biofilms that have already settled on pipes. The plat count method was used to check the antifungal activity of thymol. Data of this experiment data have shown that thymol may prevent Candida albicans and Aspergillus niger proliferation in the experimental arrangement. After just a week, a significant reduction (P<0,05) was shown with the concentration 1 g.l^-1. The reduction was much important when the product was used at a concentration of 2 g.l^-1 (about tree log units). For curative treatment, results showed a significant reduction (P<0,05) of C. albicans load after only 24 hours with 1 g.l^-1 (about one log unit). With this same concentration, reduction is more important over time for both spices (about four log units after a week). A significant reduction (more than two log units) was showed in just 24 hours of treatment with the concentration of 2 g.l^-1. This work offers an alternative solution to chemical biocides, which can treat water and disinfect distribution system in poultry farming.