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 Al 3+ , Cu 2+ , and Zn 2+ inhibited the chitinase activity, whereas Ca 2+ , Mn 2+ , and Mg 2+ promoted the activity. The chitinase was active on p -NP-GlcNAc with apparent K m value of 152.83   μmol/L and V m value of 49.12   μmol/L   min 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 15.2   g of GlcNAc production from 100   g of crayfish shell following chitinase degradation for 36   h.