Cytochrome P450-mediated biotransformation of octocrylene in Tetradesmus obliquus: Integrative insights from...

Octocrylene (OC), a sunscreen active ingredient, has received considerable attention due to its widespread occurrence and toxicity. However, little is known about its removal efficiency, elimination routes and the associated mechanisms by microalgae. Here, we investigated the removal efficiency, biotransformation products, pathways, and the cytochrome P450 (CYP450) catalytic reaction mechanism of OC by Tetradesmus obliquus. We found that Tetradesmus obliquus removed approximately 95 % of OC within 10 days, with biotransformation (82 %-99 %) being the primary removal route. Ten transformation products (TPs) were identified, of which mono-hydroxylated TPs accounted for 54.1 % of the total abundance. Transcriptomics and proteomics results both revealed that the expression of seven CYP450s was significantly upregulated, six of which were CYP26-like proteins. Furthermore, the non-specific CYP450 enzyme inhibitor 1-aminobenzotriazole (ABT) significantly inhibited the OC biotransformation rate, demonstrating the involvement of CYP450 in the biotransformation of OC in Tetradesmus obliquus. Molecular docking and DFT calculations jointly revealed that the specific binding conformation of OC with CYP26-like favored alkyl chain hydroxylation. Our findings demonstrate that Tetradesmus obliquus can efficiently degrade OC, providing new insights for developing green and sustainable removal methods for emerging contaminants like OC.