Studies On The Mutation Breeding Of L-serine-producing Strain And Its Fermetation Conditions

L-serine is a kind of nonessential amino acid, which take part in many physiological activities in human bodies. L-serine is an amino acid which is wildly applied to the pharmaceutical, the cosmetic industries and the food industries.So attempts to directly produce L-serine from the sugar sources become more attractive. and it's very significant to select a mutant strain which can produce high level L-serine from sugar sources.In our study,We obtained a mutagenized strain which can produce high level L-serine by mutation. then the optimization of fermentation condition was studied, at last, we make a conclusion:A strain, which was named C. glutamicum SYPS-062, could produce L-serine from sugar sources, after separation, A strain named C. glutamicum SYPS-062-36 was obtained, the inheritance of this stain which can accumulate L-serine 6.65g/L was steady. so this strain was intended to be original strain.We first reported that D-serine was suitable for the analog of L-serine. After twice treatments with DES to the the original strain, Finally a strain named C. glutamicum SYPS-062-33a-18 which could accumulate 11.0g/L of L-ser was obtained, and the product was increased 65.4% compared with the original strain.We also studied the effect of the medium composition on L-serine production in flask by single-factor experiment and the method of RSM, the optimal medium compositions were determined as: sucrose 83 g/L, (NH4)2SO4 30 g/L, calcium carbonate 30g/L. MgSO4·7H2O 0.5g/L, FeSO4·7H2O 0.02g/L, MnSO4·H2O 0.02g/L, VB1 100μg/L, biotin 33μg/L. thereamong, the concentration of sucrose was raised to 83g/L from 60g/L.The effect of cultivation conditions was studied. Research showed that the optimal ages of inoculums was 24h, and the optimal inoculation quantity was 5%.The strain could accumulate 16.4g/L of L-serine when the medium volume in 250mL flask was 10mL.