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.