Comparing the activity and interactions of the antifungal protein PeAfpA with conventional fungicides and food preservatives against mycotoxigenic fungi

Prevention of fungal contamination and the occurrence of mycotoxins in food and feeds requires the development of new antifungal approaches. The antifungal proteins (AFPs) produced by some fungi provide great potential for the control of contaminating fungi. In the present study, the antifungal activity of the protein PeAfpA from Penicillium expansum was compared with fungicides used in post-harvest control (imazalil and thiabendazole) and food preservatives (calcium propionate, sodium, sodium benzoate, potassium sorbate, and natamycin), against 23 fungal species belonging to the genera Penicillium, Fusarium, Byssochlamys, Aspergillus and Alternaria. In general, PeAfpA had the lowest minimum inhibitory concentration (MIC) followed by natamycin, the fungicides, and the chemical preservatives. PeAfpA was able to completely inhibit the growth of all tested fungi at concentrations ranging from 0.5 to 8 mu g mL-1. In addition, we assessed the effects of PeAfpA in combination with imazalil, thiabendazole, natamycin, or potassium sorbate against four representative fungal species. Our results provide evidence for partial synergistic and additive effects between the protein PeAfpA and the other compounds tested. This study concludes that PeAfpA, alone or in combination with fungicides or food preservatives, has a great potential to prevent fungal contamination and reduce the required dosage of fungicides or chemical preservatives used in food conservation.