Studies On Screening And Fermentation Of High Proteinase Producing Strain UF366 Aspergillus Oryzae

The protoplasts of Aspergillus Oryzae was compoundly treated with UV irradiation and lithium chloride. The mutant strain UF366 with high proteinase production was isolated. The culture medium and fermented condition and the influence factors of high proteinase producing strain UF366 were studied. The conditions of preparation and regeneration of the Aspergillus Oryzae were studied. The results were as follows: the mycelia was cultured for 10h,then enzymelysed for 90 min at 30℃.HCM was received as dissolving complete medium in 0.8 mol/l sodium chloide solution. The forming number of protoplasts was 7×106 /ml while the regeneration frequency was 27.8%. The mutation conditions : the distance is 28 cm, the time of irradiation is 60s with 30W ultraviolet lamp, the concentration of lithium chloide solution was 8%. One hundred colonies was picked up,and the strain of UF366 Aspergillus Oryzae was screened with high proteinase activity, the neutral proteinase activity have improved 33% than the original strain. The culture medium was consisted of bran, flour and water, meanwhile, the seed culture medium was made of bean cake, bran and water, the proportion is 6:4:5, the conditions of fermentation were as follows: the optimum temperature was 33℃, fermented 32 hours, twice stirring koji, 4‰inoculation amount. The strain of UF366 Aspergillus Oryzae has good hereditary stability by inoculating twenty times The optium pH value and temperature of the proteinase activity were 7.2 and 40℃, the proteinase activity lose completely when the temperature reached 90℃in 30 minutes. The result of fermented experiments were as follows,the amino acid nitrogen and total nitrogen have improved 36.7% and 39% respectively, it was necessarily to be experimented repeatedly in the batch production.