Metabolic rewiring of Phanerochaete chrysosporium to enhance tolerance and degradation of aged polystyrene microplastics: Pyruvate metabolism and actin polarization.

Recalcitrant microplastics (MPs) persist in the environment due to the chemical inertness. However, there is a lack of in-depth understanding regarding the environmental fate of MPs after aging, particularly with respect to the effects of biotransformation. This study investigates the potential for degradation of polystyrene MPs (PSMPs) by P. chrysosporium following photoaging. Results indicate that photoaging enhanced the hydrophilicity (the contact angle decreased from 98.00 ± 0.15° to 74.95 ± 0.75°) and specific surface area of PSMPs by promoting fragmentation, surface roughening, and the incorporation of oxygen-containing functional groups (the carbonyl index and hydroxyl index were increased by 5.74-fold and 2.28-fold, respectively). These changes in MPs characteristics facilitated mycelial colonization and enzymatic degradation, resulting in a significant increase in the biodegradation efficiency of PSMPs from 13.76% (pre-aging) to 20.92% (post-aging) (p < 0.01). Meanwhile, aged MPs leached cytotoxic compounds (such as phenols and additives) and exacerbated the oxidative stress in P. chrysosporium. Furthermore, analysis based on transcriptomic data, P. chrysosporium alleviates oxidative stress caused by the leachate by upregulating the expression of genes such as katE and CAT (upregulated by 2.31-fold in the F+AMPS group), and clears and repairs damaged proteins by upregulating genes such as HSP90 and DOA1 (upregulated by 1.09-fold and 2.92-fold). At the same time, the upregulation of TBP and TFIIF2 (upregulated by 4.67-fold and 1.63-fold) accelerates the overall transcription process, while the upregulation of PDC and adhP (upregulated by 1.15-fold and 1.35-fold) (p < 0.05) ensures the energy supply for transcription and degradation processes, ultimately enhancing degradation efficiency. This study elucidates the positive role of photoaging in biodegradation, providing a theoretical basis for explaining the discrepancy between the environmental fate of recalcitrant MPs in natural settings and laboratory results.