Selection of Biochemical Mutants That Overproduce Nuclease P1 and Optimization of the Fermentation Conditions

Based on the means of mutations with 60Co γ-ray and nitrosoguanidine (NTG), A high nuclease P1-producing strain HEP2312 was successfully screened when the original strain ATCC14994 treated by the method of repeat selection. Medium for fermentation and conditions were optimized by single factor and orthogonal experiments. The results showed the enzyme preparation contained a nuclease P1 activity of 1508 U/mL, when the mutant strain was cultivated with 30℃, initial pH at 6.0, rotary shaker at 120 r/min, for 48h, and in the medium consisted of 5.0% sugar, 0.3% yeast extract, 0.3% peptone, 0.6% K2HPO4, 0.6% KH2PO4, 0.2% MgSO4 and 0.2% ZnSO4.