Pyrene degradation by marine-derived ascomycete: process optimization, toxicity, and metabolic analyses

Marine-derived fungi are relevant genetic resources for bioremediation of saline environments/processes. Among the five fungi recovered from marine sponges able to degrade pyrene (Py) and benzo[a]pyrene (BaP), Tolypocladium sp. strain CBMAI 1346 and Xylaria sp. CBMAI 1464 presented the best removal rates of Py and BaP, respectively. Since the decrease in BaP was related to mycelial adsorption, a combined strategy was applied for the investigation of Py degradation by the fungus Tolypocladium sp. CBMAI 1346. The selected fungus was able to degrade about 95% of Py after 7 days of incubation (optimized conditions), generating metabolites different from the ones found before optimization. Metabolites and transcriptomic data revealed that the degradation occurred mainly by the cytochrome P450 pathway. Putative monooxygenases and dioxygenases found in the transcriptome may play an important role. After 21 days of degradation, no toxicity was found in the optimized culture conditions. The findings from the present study highlight the potential of marine-derived fungi to degrade environmental pollutants and convey innovative information related to the metabolism of pyrene.