A novel fungus Penicillium crocicola LF-2022 for high-efficiency biodegradation of brominated flame retardants: Performance, pathways, soil remediation, and transcriptomic mechanisms

Tetrabromobisphenol A (TBBPA) and decabromodiphenyl ether (BDE-209) are typical brominated flame retardants (BFRs) with environmental persistence, bioaccumulation potential, and high toxicity, posing serious threats to ecosystems and human health. In this study, a novel fungal strain, Penicillium crocicola LF-2022 ( P. crocicola LF-2022), was identified, exhibiting excellent biodegradation capabilities toward both BFRs. Within six days, the strain achieved maximum degradation rates of 81.1% for TBBPA and 97.7% for BDE-209. The strain degraded both pollutants via intracellular and extracellular pathways, with cytochrome P450 enzymes playing a key role. Degradation pathway analysis revealed that TBBPA was degraded through reductive debromination and isopropylidene bridge cleavage, whereas BDE-209 underwent sequential debromination, ether bond cleavage, and ring-opening reactions, ultimately leading toward mineralization. In soil remediation experiments, P. crocicola LF-2022 effectively degraded TBBPA and BDE-209 even under non-sterile conditions, achieving approximately 55.3% and 82.9% degradation, respectively, demonstrating strong contaminant detoxification capability. Seed toxicity evaluation confirmed the detoxification efficacy of the fungal treatment. After remediation, wheat seedling root and shoot lengths increased markedly compared with untreated controls. Moreover, malondialdehyde content in plant tissues decreased significantly, while superoxide dismutase, peroxidase, and catalase activities recovered to near-control levels, indicating substantial BFR detoxification. Transcriptomic analysis revealed distinct degradation strategies: TBBPA stress upregulated genes related to membrane integrity, ABC transporters, CYP450 monooxygenases, and antioxidant enzymes, whereas BDE-209 stress induced upregulation of secreted hydrolases, lipoxygenases, and cAMP/Ras signaling components. Collectively, this study provides a robust, stress-tolerant fungal strain for efficient BFR degradation and establishes a foundation for the bioremediation of BFR-contaminated sites under non-sterile conditions.