Inhibitory effect of the Penicillium chrysogenum antifungal protein on different zygomycetes

Abstract number: 1134_04_67

Galgoczy L., Papp T., Leiter E., Pocsi I., Vagvolgyi C.

Objectives:  

Cases of zygomycosis (the opportunistic fungal infection caused by the members of Zygomycetes) increased dramatically over the past several years. Therefore, there is a substantial demand for new-type compounds with antifungal activity against the pathogenic species of Zygomycetes. The filamentous fungus Penicillium chrysogenum secretes a small, highly basic and cysteine-rich antifungal protein named PAF. This protein inhibits the growth of some filamentous fungi, including opportunistic human pathogens and phytopathogens. PAF induces a typical hyphal tip branching, oxidative stress and K+-efflux in the sensitive strains.

Methods:  

The effect of PAF on 21 fungal isolates representing 16 different genera has been investigated. Aspergillus niger and A. terreus were used as control for a PAF sensitive and a PAF insensitive strain, respectively. The effect of PAF on germination efficiency of sporangiospores was examined in different culture media. Untreated sporangiospores were plated as controls. An agar diffusion technique was used to estimate the size of inhibition of hyphal extension by PAF.

Results:  

The Mucor, Actinomucor, Cokeromyces, Gilbertella, Rhizopus, Saksanea and Syncephalastrum strains tested were practically insensitive to PAF independently of the culture conditions and inhibition tests applied. On the other hand, Absidia, Micromucor, Mortierella, Mycotypha, Rhizomucor, Rhizopus, Thamnostylum and Umbellopsis were sensitive to PAF. The PAF-sensitivity of some of the zygomycetes depended on the culture medium and the inhibition test selected, e.g. in the case of M. africana, R. pusillus and U. isabellina, the inhibitory effect was usually weaker on hyphal growth than on sporangiospore germination.

Conclusion:  

Among the zygomycetes considered as opportunistic human and/or animal pathogens, PAF was effective against Absidia, Mortierella, Rhizomucor and Rhizopus. These results support the assumption that PAF and similar low molecular mass basic antifungal proteins produced by filamentous fungi should be considered as promising candidates in future antifungal drug research.