Enzymatic hydrolysis of chitin pretreated by bacterial fermentation to obtain pure: N -acetyl-d-glucosamine

In this study, we propose a novel biological fermentation method to process chitin powder utilizing the bacteria Chitinolyticbacter meiyuanensis SYBC-H1. The chitin obtained from this process is called CBF, and it was further investigated for N-acetyl-d-glucosamine (GlcNAc) enzymatic production. This fermentative treatment caused chitin powder to acquire a visible fleecy structure, and scanning electron microscopy showed that the surface of the CBF was a fiber-like structure with a diameter ranging from 10 nm to 200 nm. Moreover, Fourier transform infrared spectrometry, X-ray diffraction and gel permeation chromatography revealed that the crystallinity and average molecular weight of the chitin clearly decreased in the absence of deacetylation following bacterial fermentation treatment. The optimal conditions for bacterial treatment of chitin were determined at 25 °C, 200 rpm, and an initial pH of 7.5 for 12 h. Additionally, 19.2 g L^-1 of GlcNAc could be obtained with a yield of 96% from 20 g L^-1 of CBF in a batch enzymatic reaction within 6 h. This new approach provided an environmentally friendly and mild method for reducing the crystallinity of chitin and enhancing GlcNAc conversion without the use of oxidants, acids, or other environment unfriendly reagents.