Zelin Hou a b 1, Yongkang Wu a 1, Yang Liu a, Ningjia Dong a, Yu Mao a, Hong Liang a, Dawen Gao a

DOI: 10.1016/j.jhazmat.2026.141848

https://doi.org/10.1016/j.jhazmat.2026.141848

Abstract

       The environmental behavior of microplastics (MPs) is influenced by both the physicochemical effects of organic matter and biodegradation processes, yet the complex interactions among these factors remain poorly understood. This study employed the Phanerochaete chrysosporium as a model strain to investigate the key role of fulvic acid in the degradation of polystyrene MPs (PSMPs) through a 21-day degradation experiment. Results indicate that fulvic acid addition significantly increased the degradation rate of PSMPs from 13.76 ± 1.44% (fungal degradation alone) to 25.49 ± 3.72% (fungal degradation enhanced by fulvic acid) (p < 0.01), while promoting the formation of carboxylic acids and ester compounds. Further validation revealed multiple mechanisms of fulvic acid action: (1) fulvic acid etches the PSMPs surface through non-biochemical processes, enhancing its bioaccessibility (contributing to 3.25% of PSMPs degradation). (2) Genes related to ribosomal assembly, energy metabolism, and stress response were significantly upregulated in Phanerochaete chrysosporium to enhance degradation capacity (contributing to 21.90% of PSMPs degradation). (3) Esterification reactions between fulvic acid and degradation intermediates accelerated the transformation pathway of PSMPs from oxides to carboxylic acids to acyl derivatives (contributing to 0.34% of PSMPs degradation). Specifically, the formation of oxidized intermediates were primarily associated with genes encoding dehydrogenases, glutathione transferase, and lipases, whereas ester products were significantly contributed by genes encoding dehydrogenases, dioxygenase, lignocellulosic enzymes, and lipases. This work elucidates a novel abiotic-biotic coupled mechanism that significantly advances the biotransformation of MPs, providing crucial insights into the environmental fate of MPs under natural conditions.

Graphical Abstract