Abstract: N-acetylornithine decatylase(NAOase), a new kind of amino acids resolving enzyme, could be cellular expressed by the recombinant strain BL21(DE3)-pET22b-argE. In order to reduce producing cost and increase soluble NAOase activity, the culture medium and inducing conditions were optimized. The results showed that the imported peptone and yeast extracts were more suitable than the native materials. Lactose of 5.0g/L could act as inducer in place of expensive IPTG The optimized carbon and nitrogen sources are: 1.0 g/L glycerol, 15.0 ml/L corn steep liquor and 5.0 g/L peptone. Most of NAOase were expressed as inclusion bodies, little as active enzymes. The proportion of the soluble expression could be increased by lowering the inducing temperature, but the yield of target protein followed was decreased. With the optimized active inducing condition of 22 ℃for 10 h, the biomass is enhanced by 1.65-fold to 6.91and the enzyme activity is increased by 5.72-fold to 392.65 U/ml in comparison with initial medium.

Key words: N-acetylornithine decatylase(NAOase), expression optimization, inclusion bodies, soluble NAOas activity