Improvement of Vitamin K₂ Production by Escherichia sp.with Nitrogen Ion Beam Implantation Induction

【摘要】 Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra.In this work,N⁺ ion beam implantation was used to enhance Escherichia sp.in vitamin K₂ yield.Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K₂yield of mutant FM5-632.The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L,that is four times that of the original strain,was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×l0¹³ions/cm².A further optimization increased the yield of the mutant by 39.7%,i.e.172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of（per liter）:15.31 g glycerol,10 g peptone,2.89 g yeast extract,5 g K2HPO₄,1 g NaCl,0.5 g MgSO₄·7H₂O and 0.04 g cedar wood oil,incubated at 33℃,pH 7.0 and 180 rpm for 120 h.更多还原

【Abstract】 Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra.In this work,N⁺ ion beam implantation was used to enhance Escherichia sp.in vitamin K₂ yield.Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K₂yield of mutant FM5-632.The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L,that is four times that of the original strain,was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×l0¹³ions/cm².A further optimization increased the yield of the mutant by 39.7%,i.e.172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of（per liter）:15.31 g glycerol,10 g peptone,2.89 g yeast extract,5 g K2HPO₄,1 g NaCl,0.5 g MgSO₄·7H₂O and 0.04 g cedar wood oil,incubated at 33℃,pH 7.0 and 180 rpm for 120 h.更多还原