Breeding Of Glutamic Producing-Producing Strain By Protoplast And Studies On Its Fermentation Conditions

According to the theory of metabolic control fermentation, the dissertation focuses on the the selection and the fermentation conditions of an L-glutamic acid strain. The main research contents and results are as follows:(1) Brevibacterium tianjinese TN631 as a the starting strain was stepwise mutated with protoplast UV.One L-glutamic acid high-producing strain TN6319 with genetic maker (FEA~r+KMA~r+SG~r ) was screened through shake tube primary screening ,shake flask second screening,genetic marker test and single clone isolation and continuous passage cultibation.this strain could produce L-glutamic 72.9g/L after fermentation 42h under the fermentation without being optimized.Genetic character of strain TN6319 was very stable.(2) The batch fermentation condition of strain TN6319 in shake flasks was studied in this dissertation.The seed and fermentation medium were optimized by orthogonal design method and single factor.(3) Base on the optimum condition of batch fermentaion,fed batch fermentation of different feeding modes was studied with TN6319 in shake flask.The optimum initial glucose concentration was 60g/L.The lowest glucose concentration was maintained 21-30g/L.The L-glutamic acid production was 114g/L after 40h.(4) Under the optimum fermentation conditions,the strain TN6319 was used as the test strain to perform the batch fermentation in 7-liter fermentor.The mutant could produce L-glutamic acid 123g/L.The production was improved by 7.9% than that of fermentation in shake flask batch.(5) Based on the best fermentation conditions in 7-liter fermentor,the 200t fermentor fermentation was performed.The L-glutamic acid production was 131.5g/L after fermentation 32h,and its inversion rate could reach 62.2%,which increased 6.5% and 13.3% respectively related to the batch fermentation in 7L fermentor and shake flask.