In this study,strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by80 MeV/u ^(12)C^(6+) ion beams.Seven mutant strains showed marked citric acid over-production records and faster...In this study,strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by80 MeV/u ^(12)C^(6+) ion beams.Seven mutant strains showed marked citric acid over-production records and faster productivity than initial Aspergillus niger 4# by shaking flash fermentation.The maximum product yield was 132.8 gL^(-1)(the H4002 strain) being a 8.8%increase to the initial strain.The scale-up experiment was carried out in a 100 L bioreactor.The mutant H4002 can accumulate 187gL^(-1) product yield of citric acid from starch liquefying supernatant.The productivity of citric acid was 2.75gL^(-1) h^(-1).So,the mutant H4002possesses rapid sugar katabolism for producing citric acid.Meanwhile,the pellet morphology kept compact and round during the whole submerged fermentation,which was suited to produce citric acid.The results indicate that mutant H4002 has potential ability to produce citric acid rapidly.展开更多
The effects of 12C＋6 ion irradiation on colony morphology and mycelia morphology, as well as on mutation rate have been studied in the B1a high-product strains （ZJAV-Y1-203） mutated by heavy ion irradiation and com...The effects of 12C＋6 ion irradiation on colony morphology and mycelia morphology, as well as on mutation rate have been studied in the B1a high-product strains （ZJAV-Y1-203） mutated by heavy ion irradiation and compared with that in the original strain （ZJAV-A-1）. After irradiating the rate of a straw hat colony type having a high ability of producing B1a in ZJAV-Y1-203 strains was higher than that found in ZJAV-A-1 strains. When strains were cultured in a liquid medium for 24 hours, the mycelium becoming thinner could be observed in all of the irradiated ZJAV- Y1-203 groups, but only in the ZJAV-A-1 groups irradiated at the dose of 50 Gy or more. The early growth of mycelium was inhibited in the ZJAV- Y1-203 group irradiated with a high dose. The highest positive mutation rate （23.5%） of ZJAV - Y1 - 203 was reached at the lower dose of 30 Gy while the highest positive mutation rate of 34.2% in ZJAV-A-1 appeared at 50 Gy. These results indicate that the effects of heavy ion irradiation still exist even in the mutated Streptomyces avermitilis, and only the dose is lower and the effects not so strong compared with the one that is first irradiated with optimized heavy ion doses. This is evidence of the one directional mutation being controlled by many more factors in a organism.展开更多
基金Supported by the Project of Science and Technology for Gansu of Chinese academic of science(KJZG-2011-002)West Light Foundation of The Chinese Academy of Sciences(2012)
文摘In this study,strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by80 MeV/u ^(12)C^(6+) ion beams.Seven mutant strains showed marked citric acid over-production records and faster productivity than initial Aspergillus niger 4# by shaking flash fermentation.The maximum product yield was 132.8 gL^(-1)(the H4002 strain) being a 8.8%increase to the initial strain.The scale-up experiment was carried out in a 100 L bioreactor.The mutant H4002 can accumulate 187gL^(-1) product yield of citric acid from starch liquefying supernatant.The productivity of citric acid was 2.75gL^(-1) h^(-1).So,the mutant H4002possesses rapid sugar katabolism for producing citric acid.Meanwhile,the pellet morphology kept compact and round during the whole submerged fermentation,which was suited to produce citric acid.The results indicate that mutant H4002 has potential ability to produce citric acid rapidly.
基金Supported by Western Light Talents Training Program of Chinese Academy of Sciences(O906050XB0)Grant Science and Technology Projects in Lanzhou(2009-2-13)
文摘The effects of 12C＋6 ion irradiation on colony morphology and mycelia morphology, as well as on mutation rate have been studied in the B1a high-product strains （ZJAV-Y1-203） mutated by heavy ion irradiation and compared with that in the original strain （ZJAV-A-1）. After irradiating the rate of a straw hat colony type having a high ability of producing B1a in ZJAV-Y1-203 strains was higher than that found in ZJAV-A-1 strains. When strains were cultured in a liquid medium for 24 hours, the mycelium becoming thinner could be observed in all of the irradiated ZJAV- Y1-203 groups, but only in the ZJAV-A-1 groups irradiated at the dose of 50 Gy or more. The early growth of mycelium was inhibited in the ZJAV- Y1-203 group irradiated with a high dose. The highest positive mutation rate （23.5%） of ZJAV - Y1 - 203 was reached at the lower dose of 30 Gy while the highest positive mutation rate of 34.2% in ZJAV-A-1 appeared at 50 Gy. These results indicate that the effects of heavy ion irradiation still exist even in the mutated Streptomyces avermitilis, and only the dose is lower and the effects not so strong compared with the one that is first irradiated with optimized heavy ion doses. This is evidence of the one directional mutation being controlled by many more factors in a organism.
