Assembly of fungal mycelium-carbon nanotube composites and their application in pyrene removal

Polycyclic aromatic hydrocarbons (PAHs) have been known for decades to threaten human health. Various physical, chemical and biological methods have been developed to remove PAHs from different matrices. Microbial biodegradation processes are thought to be effective and environmentally friendly, but the low bioavailability of PAHs and their slow removal rate often limit the application of biodegradation. In this study, novel self-assembled PAH-degrading fungal mycelium (Penicillium oxalicum SYJ-1)-carbon nanotube (CNT) composites were applied for pyrene removal. The addition of CNTs did not affect the growth of strain SYJ-1 and promoted the total PAH removal efficiency. The composite could completely remove pyrene at 20 mg L^-1 within 48 h, while the sole fungus and CNTs alone could only remove 72% and 80% of pyrene at 72 h, respectively. A cytochrome P450 inhibition experiment, together with degradation product identification and transcriptomic analysis, suggested that an intracellular PAH transformation pathway was employed by strain SYJ-1. The versatility of this assembly approach was also confirmed by adding different nanomaterials and using them to remove different pollutants. This study provides a strategy of coupling the chemical adsorption and biodegradation capacity of inorganic nanomaterials and microorganisms as composites to treat hydrophobic substrates in restricted bioreactor.