Isolation of PAH dwelling Penicillium for application in bioremediation processes

Fungi represent the living dominant biomass in soils and are abundant in aqueous systems. In addition, they possess a high potential for degrading environmental organic chemicals. The aim of this study is to find polycyclic aromatic hydrocarbon (PAH) degrading fungi, which are adapted to polluted environments, using culturing-based techniques. In this study, a total of 12 fungal cultivable species have been isolated from a PAH contaminated pond. The isolated fungi were genetically identified by amplifying, cloning and further sequencing fragments corresponding to the ITS1-5.8S-ITS2 (internal transcribed spacer ITS) region of each cultivable fungal strain. We tested their ability to convert anthracene, in time courses of 42 days. Among the 12 screened fungal species, Penicillium oxalicum showed remarkable conversion ability, degrading 100 μM in 5 days in a rich carbon source medium. The use of a defined mineral medium with 13C-labelled anthracene showed that P. oxalicum can cometabolize anthracene, leading to the formation of anthraquinone, anthrone and hydroxyderivatives, as revealed by nuclear magnetic resonance (NMR) analysis. The last metabolites could indicate the further ring cleavage of anthracene that could be mediated by hydrolase or dioxygenase enzymes. The conversion level of anthracene was reduced to 50% in presence of an inhibitor of cytochrome P450 monooxigenase, suggesting its participation in the first oxidation step. Our results show the high effectiveness in PAHs conversion by the isolated fungi P. oxalicum by cometabolic strategies, indicating its potential application in biotechnological pollutant removal processes.