Method for enzymatic preparation of R-3 aminobutyric acid

An R-3-aminobutyric acid production strain expressing a polypeptide, wherein the polypeptide is an exogenous aspartase derived from E. coli and is used to catalyze a stereoisomeric catalytic reaction as shown below:

• wherein the exogenous aspartase is a mutant having 90% sequence identity to the amino acid sequence of SEQ ID NO:
• 5, possessing two to four amino acid mutations in the amino acid sequence corresponding to the wild type aspartase shown in SEQ ID NO:
• 5;
• or
• wherein the exogenous aspartase is a mutant having an amino acid mutation selected from the group consisting of threonine (T) at position 204, methionine (M) at position 338, Lysine (K) at position 341, asparagine (N) at position 343, and a combination thereof.