Breeding Of Valine-Producing Strain By Protoplast Fusion And Studies On Fermentation Conditions

According to the theory of metabolic control fermentation, the dissertation focuses on the breeding and fermentation condition of L-valine high-yielding strain. The main research contents and results are as follows:(1) The optimum conditions of protoplast fusion of Brevibacterium flavum TV1053 and Brevibacterium flavum TV826 were dermined. 86 fusion hybrids were got by the method of protoplast fusion with Brebibacterium flavum TV1053 and Brebibacterium flavum TV826 as the parent strains. Finally one L-valine high-producing TV02256 was screened. The strain could produce L-valine 26g/L under the fermentation condition without being optimized. Genetic character of Strain TV02256 was very stable.(2) The batch fermentation condition of the L-valine high-producing strain in shake flask was studied in this dissertation. The seed medium was optimized by orthogonal design experiment,and the seed culture conditions were also studied. The fermentation medium was optimized by the method of principal component analysis and fermentation conditions were studies. Under the optimum condition, the strain TV02256 could produce L-valine 39.4g/L by shaking flask batch fermentation.(3) Based on the above optimum condition, the batch fermentation was performed in 20000-liter fermentor. And the optimal fermentation conditions were got.