Efficient enzymatic hydrolysis of ionic liquid pretreated chitin and its dissolution mechanism

Jing Li; Wen-Can Huang; Li Gao; Jianan Sun; Zhen Liu; Xiangzhao Mao

doi:10.1016/j.carbpol.2019.02.027

Efficient enzymatic hydrolysis of ionic liquid pretreated chitin and its dissolution mechanism

Carbohydr Polym. 2019 May 1:211:329-335. doi: 10.1016/j.carbpol.2019.02.027. Epub 2019 Feb 10.

Authors

Jing Li¹, Wen-Can Huang¹, Li Gao¹, Jianan Sun¹, Zhen Liu¹, Xiangzhao Mao²

Affiliations

¹ College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China.
² College of Food Science and Engineering, Ocean University of China, Qingdao 266003, China; Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266200, China. Electronic address: xzhmao@ouc.edu.cn.

PMID: 30824097
DOI: 10.1016/j.carbpol.2019.02.027

Abstract

Colloidal chitin, the substrate of chitinase with an open hydrated gel-like structure, can be obtained by treatment using either traditional hydrochloric acid (HCl) or ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]). IL-pretreated chitin provided an efficient production of N-acetylglucosamine (175.62 mg g chitin) and N,N'-diacetylchitobiose (341.70 mg g chitin) with a conversion of 61.49% at 48 h catalyzed by chitinase from Streptomyces albolongus ATCC 27414. A short time second homogenization treatment after IL pretreatment can increase the conversion to 76.11%. A comprehensive characterization and comparison of chitin with different pretreatments suggested that enzymatic performances were correlated with the structural changes (size of the grains and porosity), high decrease in crystallinity, and high enzyme adsorption. The NMR spectroscopy studies of N-acetylglucosamine solvation in [Emim][OAc] clearly suggest that hydrogen bonding is formed between the hydroxyls of N-acetylglucosamine and both the anions and cations of the IL.

Keywords: 1-Ethyl-3-methylimidazolium; Chitin; Chitinase; Ionic liquid; Streptomyces albolongus.