Tyrosinase-functionalized polyhydroxyalkanoate bio-beads as a novel biocatalyst for degradation of bisphenol analogues

Abstract

Bisphenol compounds are emerging contaminants of high concerns with known endocrine-disrupting effects. Biocatalysis provides a green chemistry alternative for advanced treatment in water reclamation. This study createda novel biocatalyst through genetically immobilizing the Bacillus megaterium tyrosinase enzyme (BmTyr) on the surface ofself-assembled polyhydroxyalkanoate (PHA) biopolymer beads (termed PHA-BmTyr) by using synthetic biology techniques and demonstrated one-pot in vivo production of the biocatalyst for effective degradation and detoxification of various bisphenol analogues for the first time. The degradation pathway of bisphenols was determined to be mediated by the monophenolase and diphenolase activity of BmTyr. Notably, biocatalytic bisphenol degradation by PHA-BmTyr could substantially reduce or eliminate estrogenic activity of the contaminants, and the degradation products had remarkably lower acute and chronic toxicity than their parent compounds. Furthermore, the PHA-BmTyr biocatalyst had high reusability for multiple bisphenol degradation reaction cycles and showed excellent stability that retained 100% and 86.6% of the initial activity when stored at 4 °C and room temperature, respectively for 30 days. Also, the PHA-BmTyr biocatalyst could efficiently degrade bisphenol analogues in real wastewater effluent matrix. This study provides a promising approach to develop innovative biocatalysis technologies for sustainable water reclamation.