Beta subunit mutated nitrile hydratase mutant and application thereof

The invention belongs to the technical field of gene engineering and enzyme engineering, and relates to a beta subunit mutated nitrile hydratase mutant and application thereof, nitrile hydratase RrNHase derived from Rhodococcus ruber CGMCC18759 is used as a parent, and a beta subunit mutated nitrile hydratase RrNHase is used as a parent; the amino acid sequence of the nitrile hydratase mutant has the following mutations relative to a parent: the 47th amino acid tryptophan of a beta subunit mutates into valine, the 98th amino acid valine of the beta subunit mutates into histidine, the 110th amino acid asparagine of the beta subunit mutates into arginine, and the 158th amino acid histidine of the beta subunit mutates into phenylalanine. The nitrile hydratase mutant catalyzes nicotinonitrile to form nicotinamide under the condition that the pH value is 7.4, the highest specific activity can reach 1284 U/mg, the specific enzyme activity of the mutant is remarkably improved by 10 times or more compared with that o