Fungal enzyme-driven precipitation polymerization: Trapping estrogenic chemicals to block vegetable contamination.

From the paper

Abstract

Estrogenic contamination in vegetable foods, along with its associated safety implications, has become a growing global concern. Trametes versicolor laccase, a robust multicopper oxidase, efficiently catalyzed precipitation polymerization, promoting the rhizoremediation of four estrogenic chemicals (ECs) in water-lettuce. Relative to the laccase-deficient control, fungal laccase-driven polymerization significantly accelerated the dissipation of estrone (E1), 17β-estradiol (E2), 17α-ethinylestradiol (EE2), and bisphenol A (BPA) in the rhizosphere solution over 36 h. This treatment increased dissipation efficiencies from 32.18 to 61.36 % to 91.07-100.00 % and elevated dissipation rate constants by 7.26-17.31 fold. Phenoxyl radicals acted as the key intermediates in the enzymatic polymerization, resulting in the formation of high molecular mass (MM), hydrophobic precipitates. The entire process is environmentally friendly, highly efficient, and non-hazardous, fully aligned with the objectives of green and low-carbon development. Especially, the large MM and strong hydrophobicity of the formed precipitates were difficult to be taken by lettuce roots and transported to aerial tissues, significantly reducing EC accumulation in edible parts of lettuce. In the laccase-deficient control, the peak concentrations of E1, E2, EE2, and BPA in lettuce roots were 80.04, 156.67, 237.60, and 123.67 μmol·kg-1, respectively, with corresponding root uptake rate constants (k2) ranging from 0.05 to 0.22 h-1. In contrast, fungal laccase-driven precipitation polymerization reduced root concentrations of these ECs by 18.65-74.04 %, modulated k2 values to 0.02-0.43 h-1, and hindered their root-to-shoot translocation. This work underscores the potential of fungal enzyme in efficiently driving the supramolecular polymerization and subsequent sequestration of ECs into non-toxic precipitates within the rhizosphere, thus blocking their bioavailability to vegetable crops and minimizing associated dietary risks.