Modified glutamate dehydrogenase and application thereof

A modified glutamate dehydrogenase (GluDH) comprising, as compared to the initial GluDH, substitutions of amino acids at positions 22, 56, 173, 175, 182, 199, 381 and 420, wherein the amino acid at position 22 is substituted with E, the amino acid at position 56 is substituted with Q, the amino acid at position 173 is substituted with G, the amino acid at position 175 is substituted with G, the amino acid at position 182 is substituted with R, the amino acid at position 199 is substituted with Y, the amino acid at position 381 is substituted with C, the amino acid at position 420 is substituted with R,

• wherein the positions are numbered by reference to SEQ ID NO:
• 1, and wherein the modified GluDH, as compared to the initial GluDH, has an increased activity for catalyzing the reaction of 2-carbonyl-4-(hydroxymethylphosphono) butyric acid (PPO) with an amino donor to generate L-glufosinate, and/or has an improved stability, and/or has an increased Vmax, a decreased Km or an increased Vmax/Km.