Characterization of extracellular chitinase from Chitinibacter sp. GC72 and its application in GlcNAc production from crayfish shell enzymatic degradation

In this study, a novel chitinase-producing bacterium Chitinibacter sp. GC72 was isolated and investigated for N-acetyl-D-glucosamine production from crayfish shell enzymatic degradation. A dimeric chitinase was purified, which had an optimal activity at a pH of 6.8 and 40°C. The metal ions Al³⁺, Cu²⁺, and Zn²⁺ inhibited the chitinase activity, whereas Ca²⁺, Mn²⁺, and Mg²⁺ promoted the activity. The chitinase was active on p-NP-GlcNAc with apparent K_m value of 152.83μmol/L and V_m value of 49.12μmol/Lmin at 37°C. Based on the hydrolysate formed, the chitinase was characterized as an exo-hydrolytic N-acetyl glucosaminidase. Furthermore, combined treatment of ultra-micro grinding and ultrasonic with direct enzymatic hydrolysis of crayfish shell for GlcNAc production was investigated, which resulted in 15.2g of GlcNAc production from 100g of crayfish shell following chitinase degradation for 36h.