OBJECTIVE To obtain a high producing fibrinolic enzyme mutant of Bacillus nattto and optimize the fermentation condition. METHODS Bacillus nattto was mutated by N+ Implantation and fermentation condition was optimized in a shaking flask. RSEULTS Under the implantation dose of 3.64× 1015 ions·cm-2, the percentage of the positive mutated strain was high. Mutant strain 234 showed excellent genic stability. The optimal culture medium and fermentation condition was as following：carbon source was glucose, nitrogen source was soybean peptone, the ratio of carbon to nitrogen was 3∶1（6% glucose，2% soybean peptone), original pH was 7, temperature was 30 ℃, innoculumon was 8%, seed liquid volume in a 100 mL flask was 20 mL.In the optimum process, the fibrinolic enzyme activity of strain 234 reached to 1 402 U·mL-1. CONCLUSION The positive mutant was excellent and mutation by N+ implantation was useful for breeding strain.
Key words
N+ implantation /
fibronolic enzyme /
Bacillus natto /
fermentation
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References
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（ 收稿日期 ： 2009-04-13 ）
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