Screening, Identification and Characterization of a Marine Chitinase-Producing Strain Gallaecimonas xiamenensis Chi34

Objective: The marine ecosystem contains the most chitin in nature, which incubates a large number of microorganisms that can degrade and utilize chitin, therefore, the degradation of chitin by marine microbial chitinase is an important way to produce high value-added chitooligosaccharides. The aim of this study was to screen a stable chitinase-producing strain from the marine mud in Lianyungang. Methods: The chitinase-producing strain Chi34 was screened by plate screening and flask shaking fermentation re-screening and identified by morphological analysis and 16S rDNA sequence analysis. Then, effects of temperature, pH, metal ions, EDTA and SDS on Chi34 chitinase were studied. Finally, the TLC experiment was taken to analyze products of colloidal chitin hydrolyzed by Chi34 chitinase. Result: The isolated strain Chi34 was identified as Gallaecimonas xiamenensis and the activity of Chi34 chitinase was 0.631 U/mL. The optimum pH and temperature for the chitinolytic activity were 6.0 and 35 ℃, respectively. Chi34 chitinase was highly activated by Na⁺, Ca²⁺, Mn²⁺, and K⁺, while inhibited by Cu²⁺, Fe³⁺, Ba²⁺, Zn²⁺, Cd²⁺, Co²⁺, EDTA, and SDS. The main products of chitin hydrolyzed by Chi34 chitinase were (GlcNAc)₂ with little GlcNAc. Conclusion: The Chi34 chitinase could hydrolyze chitin to produce (GlcNAc)₂ and GlcNAc, which would provide a certain theoretical reference for the high value utilization of chitin.