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

•An efficiency chitinolytic bacterium Chitinibacter sp. GC72 was isolated.•First report on the characterization of the Chitinibacter sp. GC72 chitinase.•Physical pretreatments were used in enzymatic hydrolysis of crayfish shell.•Optimal conditions led to a nearly 100% GlcNAc yield from crayfish shell.

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 Km value of 152.83 μmol/L and Vm 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.