Fed-Batch Fermentation of L- Threonine by Escherichia Coli Supplemented with B-Vitamins

B-vitamins can be used as cofactors in the synthesis process of L-threonine.Concentration of the cofactor can effectively change the activity of specific enzymes and reallocate the distribution of carbon substances in the cells.Theeffects of B-vitamins, including calcium pantothenate ( 5 VB ), cobalamin ( 12 VB ), choline chloride ( 4 VB ) and nicotinamide ( 3 VB ), on L-threoninefermentation by fed-batch culture of Escherichiacoli JLTHRin a 5L fermentorwere investigated.The results showed that the production of L-threonine was increased to 133.4 g/L, which was increased by 7.8% when supplemented with 1 g/L 4 VB .The production of L-threonine was increased to 130.6 g/L, which was increased by 5.6% when supplemented with10mg/L 3 VB .At last, when a combination of 1g/L 4 VB and 10mg/L 3 VB was added to the glucose solutionwith1.5g/Lbetainehydrochloride, 138.4g/LL-threonine was accumulated, which was increased by 11.9%.