Enzymatic hydrolysis of chitinous wastes pretreated by deep eutectic solvents into N-acetyl glucosamine

•A cocktail of chitinolytic enzymes was developed to efficiently produce GlcNAc from chitin.•An efficient and green extraction-pretreatment integrated process was established using deep eutectic solvent (DES).•The chitin extraction process from chitinous wastes using DES was proved as an universal and reusable approach.•Chitin pretreated by DES exhibited 2–6-fold hydrolysis efficiency better than raw chitinous wastes. In this study, we present an efficient and green extraction-pretreatment integrated approach for enhancing enzymatic conversion of chitinous wastes into N-acetyl-d-glucosamine (GlcNAc). Firstly, the enzyme cocktail containing a chitinase CmChi1 and a N-acetyl glucosaminase CmNAGase were constructed for hydrolyzing chitin into sole GlcNAc. Secondly, deep eutectic solvent (DES), consisting of choline chloride and glycollic acid was used to treat chitinous wastes. Under optimal conditions, chitin yield reach to 72 % with a purity of 98 %. Fourier-transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction analysis revealed that the crystallinity and thermal stability of the obtained chitin decreased upon DES treatment without alteration of the chemical structure or deacetylation. Finally, the concentration of GlcNAc was increased 2–6 folds by enzymatic hydrolysis of DES-treated chitinous wastes (including shrimp shell, crab shell, ganoderma spores wall, and mycelium). The process provides a promising strategy for degrading chitinous wastes to produce high valued GlcNAc. [Display omitted]