title: Strain improvement of Streptomyces roseosporus for daptomycin production by rational screening of He-Ne laser and NTG induced mutants and kinetic modeling.
abstract: To improve the yield of daptomycin by Streptomyces roseosporus, a method of rational screening of He-Ne Laser and N-methyl-N-nitro-N-nitrosoguanidine (NTG)-induced mutants was employed in this work. Under the optimal mutagenesis conditions (NTG of 0.3 mg/L, 40 min; irradiation at 15 mW, 15 min), two steps of combined mutations were conducted. Screening of mutants was done according to the individual resistance to n-decanoic acid and daptomycin. A mutant strain LC-54-16, with the highest daptomycin production ability of 616 mg/L was obtained, which was over 5 times higher than the wild strain LC-52-6. The transcription levels of the main dpt genes in the mutant were approximately five times higher than those in the wild. The superiority of the mutant to the wild strain was further proved by the comparative studies on the kinetics of the mutant and the wild. The decrease of the inhibition of substrate and product was further confirmed, as well. It was concluded that the method of rational screening of He-Ne Laser and NTG-induced mutants could efficiently improve the daptomycin production ability of S. roseosporus.
authors.affiliation: Department of Biochemical Engineering, School of Chemical Engineering and Technology, Tianjin University, People's Republic of China.
authors.forename: Guanghai
authors.initials: G
authors.lastname: Yu
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Jia
authors.forename: Jianping
authors.initials: J
authors.lastname: Wen
authors.forename: Wenyu
authors.initials: W
authors.lastname: Lu
authors.forename: Guoying
authors.initials: G
authors.lastname: Wang
authors.forename: Qinggele
authors.initials: Q
authors.lastname: Caiyin
authors.forename: Yunlin
authors.initials: Y
authors.lastname: Chen
mesh_terms: D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D016001:Confidence Intervals; D017576:Daptomycin / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology; D003652:Decanoic Acids / Q000494:pharmacology; D025141:Drug Resistance, Fungal / Q000187:drug effects; D005285:Fermentation / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D005820:Genetic Testing; D007700:Kinetics; D054020:Lasers, Gas; D008769:Methylnitronitrosoguanidine; D050296:Microbial Viability / Q000187:drug effects; D008954:Models, Biological; D016296:Mutagenesis / Q000187:drug effects; D009154:Mutation / Q000235:genetics*; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013302:Streptomyces / Q000187:drug effects / Q000235:genetics*; D013997:Time Factors
chemical_list: D003652:Decanoic Acids; D008769:Methylnitronitrosoguanidine; C031071:decanoic acid; D017576:Daptomycin