Genome sequence and chitinases repertoire of the Chitinibacter sp. strain GC72: Heterologous expression and characterization of the chitinase (Chi1) for degradation of chitinous waste.

In this work, a GH18 chitinase (Chi1) with highly hydrolytic activity was identified from Chitinibacter sp. GC72 and successfully cloned and expressed in Escherichia coli BL21(DE3). The recombinant Chi1 exhibited specific activities of 362.6 U/mg against colloidal chitin and 56.7 U/mg against raw α-chitin. Analysis of hydrolysis pattern showed that Chi1 is a multifunctional chitinase, which mainly exhibited processive exo-acting activity with some endo-acting and N-acetyl glucosaminidase activities. Structural analysis and molecular docking were conducted to explore the potential mechanism underlying the highly and multiple activities. Furthermore, Chi1 was utilized to convert raw α-chitin into reducing sugar affording 48.6% (w/w) yield of total sugar with a 1:4 molar ratio of NAG to NAG, while also displaying hydrolysis activity to chitinous biomass with 4.1% sugar yield. This study provides a potent chitinase to hydrolyze chitinous resource with unusual product pattern, showing great potential for further industrial applications.