Widespread distribution of BpfA-mediated bisphenol F degradation among members of the <i>Pseudomonadota</i> and <i>Actinomycetota</i>

Bisphenol F, a widely used primary raw material in the production of polycarbonate and epoxy resins, is frequently detected in the environment and poses significant risks to ecosystems and human health. Microorganisms play an important role in bisphenol F degradation in the natural environment; however, the genetic determinants involved remain unknown. A flavoprotein oxidase BpfA from Microbacterium sp. strain F2 was identified in this study, which is responsible for the crucial steps of bisphenol F degradation involving its conversion to 4,4'-dihydroxybenzophenone through three consecutive reactions. BpfA phylogenetically clusters within the 4-phenol oxidizing subfamily of the vanillyl alcohol oxidase/para-cresol methylhydroxylase flavoprotein family. Three homologs in this subfamily-vanillyl alcohol oxidase VAO, eugenol oxidase EUGO, and flavoprotein oxidase FBO-shared over 35.0% identity with BpfA and demonstrated bisphenol F-degrading activity, yet the catalytic efficiency of BpfA against bisphenol F (508.1 mM-1 s-1) was significantly higher than that of vanillyl alcohol oxidase VAO (0.2 mM-1 s-1), eugenol oxidase EUGO (0.2 mM-1 s-1), and flavoprotein oxidase FBO (0.3 mM-1 s-1). Structural analysis indicated that strong active site hydrophobicity was likely the reason for this high catalytic efficiency. Bioinformatics-based taxonomic profiling revealed that candidate bisphenol F degraders carrying bpfA mainly belonged to the Pseudomonadota and Actinomycetota phyla, and were predominantly found in metagenomes from cultivated land and forests. This study elucidated the function and distribution pattern of bpfA, enhancing our understanding of microbial bisphenol F degradation in the environment.