Millions of tons of shrimp and crab waste, rich in chitin, are produced annually worldwide. To efficiently utilize this resource and address the contamination caused by traditional chitin treatment, a high-chitinase-producing strain, GXMU-J23.1, was isolated from the marine environment and identified as Bacillus paralicheniformis. Genome sequencing revealed several chitinolytic enzymes, such as chitinase, chitin deacetylase, and polysaccharide monooxygenases. Under optimal conditions, the chitinase activity increased 9.1-fold to 356.32 ± 1.21 U/mL. The purified chitinase Chi23 exhibited optimal activity at 50 °C and pH 5.0, degrading various chitin substrates. Metal ions such as Ca2+ and reagents such as EDTA increased the activity, whereas Fe2+ and Zn2+ inhibited the activity. Chi23, an endochitinase, converts chitin into chitotriose and diacetylchitobiose. Based on the structural reconstruction and molecular docking of Chi23, the potential enzyme-substrate mode of action was elucidated, which will support subsequent enzyme modification and in-depth development of enzyme systems assisting in chitin degradation.
Keywords: Biotransformation; Chitooligosaccharide; Draft genome; Enzymatic properties; Homology modeling.
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