Evaluation of the Antifungal Activity of Sulfur and Chitosan Nanocomposites with Active Ingredients of Ruta graveolens, Thymus vulgaris and Eucalyptus melliodora on the Growth of Botrytis fabae and Fusarium oxysporum
The purpose of this research was to determine the inhibitor effects of nanocomposites over two pathogenic fungi: Botrytis fabae Sard and Fusarium oxysporum isolated from bean crops. These nanocomposites were prepared with elemental sulfur nanoparticles coated with essential oils (four levels, three oils) and further stabilized with chitosan. The research was conducted in the microbiology laboratory of CENCINAT. We evaluated 12 nanocomposites at room temperature and PDA plates at pH 4 for 10 days and compared to controls with no nanocomposites additions. Data for statistical analysis were gathered starting from the seventh growth day because of the fungi efficient growth without treatment is between the fourth and fifth day, respectively. Statistical experimental analysis were carried out through a complete randomized block design using each Petri dish, with spots with 4 nacomposites in each spot. A total of 12 final different nanocomposites were used for all assayed plates giving five repetitions, four replicates and two fungi to carry out ANOVA analysis. Significant differences measures on fungal growth in each treatment, were compared according to Docimo Dunca's multiple range for p <0.05 using the statistical package InfoStat Professional. The independent analyzed variables were Fusarium oxysporum, Botrytis fabae Sard and different essential oils produced by Ruta graveolens, Eucalyptus melliodora, Thymus vulgaris and concentrations of each oil (20% 40% 60% 80% The results indicate that the nanocomposites application over the fungi in vitro could be effective according to the fungi species. F. oxysporum is the most inhibited by applying the nanocomposite with common rue or thyme oil 40% (optimum concentration) while 60% and 80% did not show any statistical difference. However, B. fabae inhibition was shown at these 60 and 80% concentrations. The nanocomposites with 20% eucalyptus displayed smaller inhibition halos against both fungi.