Abstract: A chitinase (named Chi-Pc76) was isolated and purified from the fermentation broth of Penicillium chrysogenum Xch23 and its application potential was evaluated. The enzyme was purified to homogeneity by consecutive ammonium sulfate precipitation, DEAE-Cellulose A52 ion exchange chromatography and Sephadex G-100 gel filtration chromatography, yielding a 17.1-fold purification with 21.6% recovery and an specific activity of 584.8 U/mg. The molecular mass of Chi-Pc76 was estimated to be 61 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The optimum pH and temperature for the purified Chi-Pc76 was 6.0 and 55 ℃, respectively. The enzyme showed high stability in the broad pH range of 4.0–10.0 and temperature stability up to 70 ℃. Chi-Pc76 exhibited high activity toward colloidal chitin and moderate activity toward glycol chitin, α-chitin, β-chitin, while it showed no or trace activity toward other tested substrates. Its Km and Vmax values for colloidal chitin were 0.25 mg/mL and 20 μmol/(min·mg), respectively. The activity of the enzyme was stimulated by Ca2+, Ba2+, Mg2+, K+, Na+ ions, but not affected by SDS, Tween 80, Triton X100, PMSF and urea. Mn2+, Co2+, Fe2+, Ag+, Cu2+, Zn2+, Pb2+ and Hg2+ and β-mercaptoethanol, as well as DTT inhibited the enzyme activity. Chi-Pc76 showed antifungal activity toward Aspergillus niger, Aspergillus flavus, Fusarium oxysporum, and P. citrinum. To the best of our knowledge, this is the first report of the antifungal chitinase from P. chrysogenum. In view of its advantages such as simple purification, high thermostability, broad-pH range stability, high-efficiency chitin-degrading ability, and antifungal activity, Chi-Pc76 will have potential applications in the comprehensive utilization of chitin waste, the bioconversion of chitin to pharmacologically active products, food preservation, and the biological control of phytopathogenic fungi and insect larvae.

Key words: chitinase; Penicillium chrysogenum; purification; enzymatic characteristics; antifungal activity