Studies On Breeding Of High Producing β-glucanase By N～+ Implantation And Optimizing Fermentation Condition

β-Glucan can be decomposed small molecules byβ-glucanase.Thus restrainable effet ofβ-glucan is eliminated. So it is being attached importance to in feed additive field.But,it's application was restricted for its low enzyme activity and complex fermentation conditions. The strain Aspergillus niger Y2449was the studing material in this experiment . Firstly, the culture medium for aβ-glucanase production by Aspergillus niger Y2449 was studied in this experiment; Than, the effects on the survival rate and the positive mutation rate by ion implantation with different parameters were studied, by a large number of screenings, one strain SD16 was breeded. Finally, the fermentation conditions of mutagenic strain SD16 were studied.By single and Orthogonal test, A culture medium for aβ-glucanase production by Aspergillus niger Y2449 was studied..From the experiment,the optimal medium consisting of 3% barley powder,2% bean cake powder and 0.14% NH4NO3 ,was obtained.β-glucan0.1%, NaHc0.1%, Vitamine0.1%, CaCO₃0.3%, K₂HPO₄.3H₂O0.1%, MgSO₄.7H2O 0.05%,FeSO₄.7H₂O 0.001%.The composition of fermentationβ-glucanase activity was 73U/ml, but original activity was 40.3 U/ml. The result suggested that N+ implantation is an effective means in screeningβ-glucanase.The effects on the strain Aspergillus niger's survival rate in vacuum in this experiment were studied. The studies indicated:The vacuum can notably influence survival rate .When the strain was deposited for 30 seconds,its survival rate was 82.7%,when180 seconds, its survival rate was 20%, when180 seconds, its survival rate was 5.4%.However,when the strain was protected by glycerin in vacuum, Its survival rate was affected indistinctivly. When the strain was deposited for 30 seconds,its survival rate was 98.2%,when 240 seconds, its survival rate was 93.3%.Then,this experiment studied about the effects on the survival rate and the positive mutation rate by ion implantation with different parameters. The resuts indicated: its survival rate was decreased slowly;The more implantation energy, the more positive mutation rate. The surviving curve of the antibiotic-producers caused by ion beam implantation was studied.It was tipical"saddle-shaped"dosage effect curve .The results showed the optimizational parameters as following:ion type-N+,ion energy-15KeV,dosage range of ion implantation: 80×2.6×10¹³ N⁺/cm².By a large number of screenings,one strain SD16 which producedβ-glucanase with activity 489.32 U/ml.Studies showed that SD16 has a good genetical stability.Finally, fermentation conditions of mutagenic strain SD16 were studied.The fermentation condition is: the optimum fermentation temperature 30℃, time, and 50ml culure medium/500 ml flask, seed volume 1.5ml, rotation speed 200rpm, pH, 6.5, fermentation time60h. The activity of protease of mutated strain Aspergillus niger SD16 was raised 512.67 U/ml.