Cloning, expression and characterization of the chitinase gene from Vibrio sp. GR52

Abstract:

[Background] Chitin is the second most abundant natural resource next to cellulose. Chitinase can catalyze chitin into chitosan oligosaccharide which achieved high value utilization of waste. [Objective] The chitinase gene of Vibrio sp. GR52 was cloned and expressed in Escherichia coli, and the properties of recombinase were characterized. [Methods] The chitinase gene chiGR52-1 was cloned from the genomic DNA of Vibrio sp. GR52 and the recombinant strain BL21 (DE3)/pET22b-chiGR52-1 was constructed. The recombinase rchiGR52-1 was purified by Ni-NTA affinity chromatography and the enzymatic properties were studied. [Results] The optimum catalytic pH of rchiGR52-1 was 6.0. It was stabled in the pH range of 5.0 to 10.0 and could maintain more than 85% of its relative activity after incubation at 37 °C for 1 hour. The optimum catalytic temperature of the enzyme was 50 °C and 60% of enzyme activity was remained after incubation at 50 °C for 1 hour. At the concentration of 1 mmol/L, Cu2+ and Ca2+ had stimulation on rchiGR52-1, while Hg+ had significant inhibition. At the concentration of 5 mmol/L, Ni+ stimulated the chitinase, while Mn2+, Co2+, Li+, Fe2+, Hg+ and SDS inhibited the enzyme. The kinetic parameters Km, Vmax and kcat of rchiGR52-1 were 0.85 mg/mL, 0.19 μmol/(mL·min) and 7.02 s?1, respectively. Substrate specificity analysis showed that rchiGR52-1 could catalyze chitin specifically. [Conclusion] Recombinant chitinase has good enzymatic properties which provide a theoretical foundation for chitinase applications.