Dissecting the effect of polyethylene glycol on the enzymatic hydrolysis of diverse lignocellulose

Natural lignocellulose is used as raw material to produce chemicals through biological transformation. The accessibility of cellulase to substrate was also one of the limiting factors of industrial production. Polyethylene glycol (PEG) can be used as additive in enzymatic hydrolysis of lignocellulose. In this study, enzymatic activity on simultaneous or non-simultaneous addition of PEG 4000 was investigated, and the partly delignified rice straw, the rice straw and filter paper were used as substrates, respectively. Enzyme activity was characterized by reducing sugar concentration in supernatant which was quantified through 3,5-dinitrosalicylic acid (DNS) method. Addition of PEG has been proven to facilitate enzymatic hydrolysis of lignocellulosic materials. Furthermore, PEG had the positive effect on hydrolytic enzyme activity of pure cellulose materials without lignin. Changes in lignocellulose materials have been observed by inverted microscope and Scanning electron microscope (SEM), and no chemical changes were shown by Fourier transform infrared spectroscopy (FTIR). The promotion of PEG on enzymatic hydrolysis of pure cellulose materials may be due to its loose physical structure and similar phenomenon in natural lignin materials. PEG loosens the physical structure of lignocellulose, thus facilitating enzymatic hydrolysis. This may be a new idea to optimize the lignocellulosic enzymatic hydrolysis process.