Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process

ABSTRACT Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08 mg mL-1) after 48 h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology.

Role of chemical components of cork on sorption of aqueous polycyclic aromatic hydrocarbons

In order to know the environmental behaviour of toxic pollutants it is fundamental to understand the role of chemical components of a material on sorption of such pollutants. In this study, the sorption of a mix of polycyclic aromatic hydrocarbons [PAHs] by cork fractions [i.e. raw cork [CF], free extractive cork [FEF] and nonsaponifiable [DESF]] has been investigated to better understand the role of biopolymers and extractable fraction of cork on their sorption behaviour. All samples were analyzed through elemental analysis and were examined using Fourier transform infrared spectroscopy. After removing the extractable fraction and the suberin from the cork, the sorption capacities [K[oc]] of FEF and DESF exhibited mean reductions of 70% and 30% respectively. In addition, the sorption results of three pairs of cork samples with different chemical content confirm that the extractable fraction serves as the major sorption medium for PAHs. Considering only low molecular weight PAHs positive correlations between K[oc] with K[ow] [R[2]=0.70] and F number [R[2]=0.65] were found, showing that these parameters are involved in this adsorption process