Cutinases catalyze polyacrylate hydrolysis and prevent their aggregation

During the recycling of waste paper, the accumulation of polyacrylates present in the waste paper causes the formation of tacky substances known as stickies. Deposition of these stickies on the machinery decreases the quality of the recycled paper and increases the usage of circulating water. Enzymes that hydrolyze these polyacrylates can minimize or eliminate the deposition of stickies. In initial experiments, the abilities of the cutinases from Humicola insolens, Fusarium solani and Thermobifida fusca to hydrolyze poly (methyl acrylate) (PMA) and poly (ethyl acrylate) (PEA) within a macroporous resin were compared. Then, to simulate the environment encountered during paper recycling, PMA and PEA dispersions were used as substrates. The decrease in turbidity was measured at a concentration of 0.5 mg mL(-1). When used at pH 8.0 and 30-50 degrees C, T. fusca cutinase limited the turbidity decrease to about 1.0% and favored the hydrolysis of PEA over PMA. F. solani and H. insolens cutinases performed best at pH 8.5 and temperatures of 35 and 50 degrees C, respectively. At a polyacrylate concentration of 0.1 mg mL(-1), the optimal temperatures of these cutinases decreased. The optimal T fusca cutinase dosage was lower than those of E solani and H. insolens cutinases. (C) 2018 Published by Elsevier Ltd.