Abstract:Objective: To clone and recombinantly express ornithine transcarbamoylase from Lactobacillus brevis and study its enzymatic properties. Methods: The gene cloning process was using Lactobacillus brevis as template which based on the gene sequence analysis. The recombinant protein was expressed in E. coli, and purified by Ni-NTA affinity chromatography column. By using arginine as substrate, the enzymatic properties were studied. Results: The optimal temperature of recombinant ornithine transcarbamoylase is 55 °C. It has excellent thermal stability at 4 °C and still retains more than 50% biological activity at 37 °C for 3 hours. However, after 40 minutes at 65 °C it will totally lose activity; the optimal pH value of the enzyme is 6.5, when the pH is alkaline, the enzyme activity decreases significantly; the enzyme possess highest activity under 5% mass fraction of NaCl and 5% volume fraction of ethanol, but the difference is not obvious, indicating recombinant ornithine transcarbamoylase has good salt tolerance and alcohol tolerance; the kinetic parameters Km is 1.58 mmol and Vmax is 5.88 mmol/min. Conclusion: The ornithine transcarbamoylase derived from Lactobacillus brevis has good temperature stability, salt tolerance and alcohol tolerance, and has certain application prospects in alcohol fermentation.