The insecticidal strain 173 was isolated from marine source and its activity was explored by the bioassay of brine shrimp and Helicoverpa armigera . Based on morphological, physiological and molecular properties, the ...The insecticidal strain 173 was isolated from marine source and its activity was explored by the bioassay of brine shrimp and Helicoverpa armigera . Based on morphological, physiological and molecular properties, the insecticidal strain 173 was identified as Streptomycetes avermitilis , which is the best insecticidal microorganism found in the terrestrial environment. The taxonomy of the strain 173, insecticidal spectrum and properties of the corresponding insecticidal antibiotics are reported.展开更多
Among eight components of avermectin,B1 fractions have the most effective antiparasitic activities and the lowest level of toxic side-effects and are used widely in veterinary and agricultural fields.In-traspecific pr...Among eight components of avermectin,B1 fractions have the most effective antiparasitic activities and the lowest level of toxic side-effects and are used widely in veterinary and agricultural fields.In-traspecific protoplast fusion between two strains of Streptomyces avermitilis,one an avermectin high producer(strain 76-05)and the other a genetically engineered strain containing the mutations aveDˉand olmAˉ(strain 73-12)was performed for enhancement and selective production of avermectin B in the absence of oligomycin.Two recombinant strains(F23 and F29)were isolated and characterized with regards to the parental merits.F23 and F29 produced only the four avermectin B components with high yield and produced no oligomycin.The avermectin production of F23 and F29 was about 84.20%and 103.45%of the parental strain 76-05,respectively,and increased about 2.66-fold and 3.50-fold,re-spectively,compared to that of parental strain 73-12.F23 and F29 were genetically stable prototrophic recombinants and F29 was quite tolerant of fermentation conditions compared to avermectin high producer parental strain 76-05.The ability to produce avermectin B with high yield without the produc-tion of other avermectin components and oligomycin will make F23 and F29 useful strains for aver-mectin production.Strain F29's tolerance of fermentation conditions will also make it suitable for in-dustrial applications.展开更多
The 2015 Nobel Prize in Physiology or Medicine has been awarded to avermectins and artemisinin,respectively.Avermectins produced by Streptomyces avermitilis are excellent anthelmintic and potential antibiotic agents.B...The 2015 Nobel Prize in Physiology or Medicine has been awarded to avermectins and artemisinin,respectively.Avermectins produced by Streptomyces avermitilis are excellent anthelmintic and potential antibiotic agents.Because wild-type strains only produce low levels of avermectins,much research effort has focused on improvements in avermectin production to meet the ever increasing demand for such compounds.This review describes the strategies that have been widely employed and the future prospects of synthetic biology applications in avermectin yield improvement.With the help of genome sequencing of S.avermitilis and an understanding of the avermectin biosynthetic/regulatory pathways,synthetic and systems biotechnology approaches have been applied for precision engineering.We focus on the design and synthesis of biological chassis,parts,devices,and modules from diverse microbes to reconstruct and optimize their dynamic processes,as well as predict favorable effective overproduction of avermectins by a 4Ms strategy(Mine,Model,Manipulation,and Measurement).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
文摘The insecticidal strain 173 was isolated from marine source and its activity was explored by the bioassay of brine shrimp and Helicoverpa armigera . Based on morphological, physiological and molecular properties, the insecticidal strain 173 was identified as Streptomycetes avermitilis , which is the best insecticidal microorganism found in the terrestrial environment. The taxonomy of the strain 173, insecticidal spectrum and properties of the corresponding insecticidal antibiotics are reported.
基金Supported by National Basic Research Project(Grant No.2003CB114205)Key Technologies R&D Programme(Grant No.2004BA713B02-03)
文摘Among eight components of avermectin,B1 fractions have the most effective antiparasitic activities and the lowest level of toxic side-effects and are used widely in veterinary and agricultural fields.In-traspecific protoplast fusion between two strains of Streptomyces avermitilis,one an avermectin high producer(strain 76-05)and the other a genetically engineered strain containing the mutations aveDˉand olmAˉ(strain 73-12)was performed for enhancement and selective production of avermectin B in the absence of oligomycin.Two recombinant strains(F23 and F29)were isolated and characterized with regards to the parental merits.F23 and F29 produced only the four avermectin B components with high yield and produced no oligomycin.The avermectin production of F23 and F29 was about 84.20%and 103.45%of the parental strain 76-05,respectively,and increased about 2.66-fold and 3.50-fold,re-spectively,compared to that of parental strain 73-12.F23 and F29 were genetically stable prototrophic recombinants and F29 was quite tolerant of fermentation conditions compared to avermectin high producer parental strain 76-05.The ability to produce avermectin B with high yield without the produc-tion of other avermectin components and oligomycin will make F23 and F29 useful strains for aver-mectin production.Strain F29's tolerance of fermentation conditions will also make it suitable for in-dustrial applications.
基金the National Program on Key Basic Research Project(973 program,2013CB734000 and 2012CB725203)the National Natural Science Foundation of China(31170095,31000057,and 31100075)+1 种基金the Ministry of Science and Technology of the People’s Republic of China(2011ZX11102-011-11 and 2013ZX10005004-005)China Ocean Mineral Resources R&D Association(DY125-15-T-07)。
文摘The 2015 Nobel Prize in Physiology or Medicine has been awarded to avermectins and artemisinin,respectively.Avermectins produced by Streptomyces avermitilis are excellent anthelmintic and potential antibiotic agents.Because wild-type strains only produce low levels of avermectins,much research effort has focused on improvements in avermectin production to meet the ever increasing demand for such compounds.This review describes the strategies that have been widely employed and the future prospects of synthetic biology applications in avermectin yield improvement.With the help of genome sequencing of S.avermitilis and an understanding of the avermectin biosynthetic/regulatory pathways,synthetic and systems biotechnology approaches have been applied for precision engineering.We focus on the design and synthesis of biological chassis,parts,devices,and modules from diverse microbes to reconstruct and optimize their dynamic processes,as well as predict favorable effective overproduction of avermectins by a 4Ms strategy(Mine,Model,Manipulation,and Measurement).
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.
