The invention relates to construction of a recombinant bacterium for efficiently expressing
chitinase and screening of a
mutant with high
enzyme activity. According to the invention, efficient secretory expression of BcchiA1 in
bacillus subtilis is realized by means of a recombinant
protein technology, and the problem of insufficient
chitinase secretion amount of most microorganisms is solved. Meanwhile, a novel
chitinase high-
throughput screening method is created, and the screening
throughput and efficiency are greatly improved. In addition, the invention relates to several strains of chitinase mutants with high
enzyme activity, the
enzyme activities of BcchiA1 (Y10A), BcchiA1 (R301A), BcchiA1 (E327A), BcchiA1 (Y10A / R301A), BcchiA1 (Y10A / E327A), BcchiA1 (R301A / E327A) and BcchiA1 (Y10A / R301A / E327A) are respectively improved by 2.49 times, 0.67 times, 3.61 times, 2.39 times, 3.46 times, 4.75 times and 16.89 times compared with the enzyme activities of the
wild type BcchiA1, and the enzyme activity of BcchiA1 (Y10A / R301A / E327A) is optimal. Finally, after the chitinase BcchiA1 and the optimal
mutant BcchiA1 (Y10A / R301A / E327A) of the chitinase BcchiA1 and the
monooxygenase BatLPMO10 from
bacillus atrophaeus are subjected to a synergistic effect respectively, the
hydrolysis efficiency of the chitinase BcchiA1 can be improved by 50.00%, and the
hydrolysis efficiency of the chitinase BcchiA1 (Y10A / R301A / E327A) can be improved by 46.71%.