Method for producing L-ornithine by microbial enzyme method

The invention discloses a method for producing L-ornithine by a microbial enzyme method, which comprises the following steps: adding human recombinant arginase I modified by site-specific mutagenesis into a substrate solution containing L-arginine, stirring and reacting for 4-6 hours under the conditions that the temperature is 25-45 DEG C and the pH value is 7.2-7.3, and converting the arginine into the L-ornithine, the substrate solution contains 80 to 120 g/L of L-arginine, 1 to 3 mg/L of pyridoxal phosphate and 0.1 to 0.2 mg/L of dimethyl sulfoxide; the amino acid sequence of the human recombinant arginase I subjected to site-specific mutagenesis modification is shown as SEQ ID NO. 5. The arginase is subjected to site-directed mutagenesis modification treatment, so that the catalytic activity of the arginase is improved; the industrial production of the arginase subjected to mutation modification is realized by constructing a production strain and optimizing a fermentation process; by optimizing the compo