CONICET | Buscador de Institutos y Recursos Humanos

Entomopathogenic fungi (EF) attack insects and consume them as a nutrient source. However, onthe cuticle of insects and in their intestine, there are numerous bacterial species that also try toconsume it, particularly when the insect dies. One of the most common organisms present onepithelia, including human skin, is Staphylococcus aureus. The objective of the present work was todetermine the MIC50 and antibiofilm activity against Staphylococcus aureus ATCC 6538 of theextracts of Fusarium sp. 3300 [NRRL 25102] ARSEF cultures produced in presence of insectfragments. The EF was grown up in potato dextrose broth (3%) in presence and absence of 1% p/v Spodoptera frugiperda traces. In addition, an uninoculated control with insect remains (1% p/v) was used. After the incubation, the mycelium and insoluble material were separated by vacuum filtration and then extracted with ethyl acetate (EtOAc) and methanol (MeOH). In addition, an EtOAc extract of the filtered supernatant was performed. Chemical profiles of the nine obtained extracts were analyzed by thin-layer chromatography (TLC). The effect of (50, 100, 200 and 400) ug/ml of the EtOAc and MeOH extracts against S. aureus growth in Müller-Hinton (MH) media was in microplate reader at 560 nm. The effects on the biofilm production were evaluated by the crystal violet micro-technique.None of the methanolic mycelium extracts was able to inhibit bacterial S. aureus growth but all of them were able to inhibit biofilm formation (between 30 ? 60%). Among the EtOAc extracts of filtered supernatant, the most potent was the one obtained in presence of insect traces (MIC50 66.7 ug/ml) and inhibiting biofilm formation by 68%.These results indicate that EF are able to produce antimicrobial compounds, probably to detect and control the accompanying flora in insects. These metabolites from eukaryote origin should be further investigated in their antibiotic potential.

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