Enzyme-catalyzed simultaneous hydrolysis-glycolysis reactions reveals tunability on PET depolymerization products

Publication date: 15 September 2018 Source:Biochemical Engineering Journal, Volume 137 Author(s): Aline Machado de Castro, Adriano Carniel, Lys Sirelli, Marcos Lopes Dias, Sonia Maria Cabral de Menezes, Luiz Silvino Chinelatto Junior, Hercilio de Angeli Honorato PET depolymerization via enzymatic catalysis is one of the most promising technologies in the context of plastics circular economy. So far, hydrolysis reactions accounted for almost the totality of studies, since the glycolysis route was only recently reported. In the present work, a comparative analysis of hydrolysis and glycolysis of PET oligomers catalyzed by Humicola insolens cutinase (HiC) and Candida antarctica lipase B (CALB) showed completely distinct profiles of the reaction products and rates. Then, simultaneous hydrolysis-glycolysis reactions with varied water and ethylene glycol concentrations revealed a gradual increase of the esterified products mono(2-hydroxyethyl) terephthalate (MHET) and bis(2-hydroxyethyl) terephthalate (BHET) as the reaction medium became more organic. Erosion patterns on the PET surface during hydrolysis and glycolysis reactions were also shown to be different. The results here reported open new opportunities for the use of task-specific solvents for biotechnological PET recycling, providing versatility for the depolymerization products in different reuse technologies. Graphical abstract
Source: Biochemical Engineering Journal - Category: Biochemistry Source Type: research