Purification and characterization of a novel antifungal protein secreted by Penicillium chrysogenum from an Arctic sediment.

A fungal strain, Penicillium chrysogenum A096, was isolated from an Arctic sediment sample. Its culture supernatant inhibited mycelial growth of some plant pathogenic fungi. After saturation of P. chrysogenum A096 culture supernatant with ammonium sulfate and ion exchange chromatography, a novel antifungal protein (Pc-Arctin) was purified and identified by matrix assisted laser desorption ionization-time of flight-time of flight-mass spectrometry (MALDI-TOF-TOF-MS). The gene encoding for Pc-Arctin consisting of 195 nucleotides was cloned from P. chrysogenum A096 to confirm the mass spectrometry result. Pc-Arctin displays antifungal activity against Paecilomyces variotii, Alternaria longipes, and Trichoderma viride at minimum inhibitory concentrations (MIC) of 24, 48, and 192 ng/disc, respectively. Pc-Arctin was most sensitive to proteinase K and then to trypsin but insensitive to papain. Pc-Arctin possesses high thermostability and cannot be antagonized by common surfactants, except for sodium dodecyl sulfate (SDS). Divalent ions, such as Mn(2+), Mg(2+), and Zn(2+), inhibited the antifungal activity of Pc-Arctin. Hemagglutination assays showed that Pc-Arctin had no hemagglutinating or hemolytic activity against red blood cells (RBC) from rabbits, rats, and guinea pigs. Therefore, Pc-Arctin from Arctic P. chrysogenum may represent a novel antifungal protein with potential for application in controlling plant pathogenic fungal infection.