Improved production of biocatalysts by Yarrowia lipolytica using natural sources of the biopolyesters cutin and suberin, and their application in hydrolysis of poly (ethylene terephthalate) (PET).

Since plastic pollution emerged as an urgent environmental problem, different biocatalysts have been tested for poly(ethylene terephthalate) (PET) hydrolysis. This work evaluated three different possible inducers for lipases and/or esterases, two natural sources of biopolymers (apple peels and commercial cork) and PET, as supplements in the solid-state fermentation of soybean bran by Yarrowia lipolytica. The obtained enzymatic extracts displaying different levels of lipase and esterase activities were then tested for PET depolymerization. Supplementation with 5 or 20 wt% of commercial cork led to an increase of 16% in lipase activity and to an increase of 131% in esterase activity, respectively. PET supplementation also led to an increase in the esterase activity of the enzymatic extracts (up to 69%). Enzymes produced in the screening step were able to act as biocatalysts in PET hydrolysis. Enzymatic extracts obtained in fermentation samples supplemented with 20 wt% PET and 20 wt% apple peels led to the highest terephthalic acid concentration (21.2 µmol L-1) in 7 days, whereas enzymes produced in commercial cork media were more efficient for bis(2-hydroxyethyl) terephthalate (BHET) hydrolysis, one of the key-PET hydrolysis intermediates. Results suggest a good potential of the biocatalysts produced by Y. lipolytica IMUFRJ 50,682 in a low-cost media for subsequent utilization in PET depolymerization reactions. This is one of the few reports on the use of a yeast for this application.