The Identification, Mutation Breeding And Fermentation Conditions' Optimizing Of A Strain Of L-Thr Producer

In this paper, threonine producing bacteria was isolated from L-threonine producing strain WS4006 which is preserved from the laboratory, the main research contents and results are as follows:1. The identification of L-threonine producing strain A L-threonine producing strain WS4006-7E is isolated from the culture of threonine producing strain WS4006, which is reserved in the laboratory. According with"Berger's Handbook on the Identification of Bacteria"and"The Handbook on the Identification of Common Bacteria", the WS4006-7E strain system classification analysis was performed using the traditional phenotype identification and the modern 16SrDNA nucleotide sequence homologous analysis, the result of identification is that the strain WS4006-7E belongs to a new strain, has a close genetic relationship of Pseudomonas maltophilia.2. L-threonine yield Strain To the isolated L-threonine producing strain WS4006-7E as a starting strain, after stepwise mutated with NTG,UV and DES, directional selection a high level of acid ammonium L-threonine producing strain WS4006-7E-NUT-21, without optimization of fermentation conditions, it can produce L-threonine 5.679 g / L.3.The batch fermentation conditions of L-threonine producing strain in shake flask were studied in this paper. Using Orthogonal experimental design, single-factor experiment design, uniform design experimental methods, application spss16.0 data processing system, L-threonine Producing Strains of the seed culture medium, fermentation medium components and fermentation conditions were optimized to determine the optimal medium composition and fermentation conditions. Under the optimum conditions, strain WS4006-7E-NUT-21 could produce L-Thr 9.878g/L after incubation for 72h by flask-shaking batch fermentation.