title: Optimization of carbon source and glucose feeding strategy for improvement of L-isoleucine production byEscherichia coli.
abstract: Fed-batch cultivations of L-isoleucine-producingEscherichia coliTRFP (SGr,α-ABAr, with a pTHR101 plasmid containing a thr operon and ilvA) were carried out on different carbon sources: glucose, sucrose, fructose, maltose and glycerol. The results indicated that sucrose was the best initial carbon source for L-isoleucine production and then sucrose concentration of 30 g·L-1was determined in the production medium. The results of different carbon sources feeding showed that the glucose solution was the most suitable feeding media. The dissolved oxygen (DO) of L-isoleucine fermentation was maintained at 5%, 15% and 30% with DO-stat feeding, respectively. The results indicated that when the DO level was maintained at 30%, the highest biomass and L-isoleucine production were obtained. The accumulation of acetate was decreased and the production of L-isoleucine was increased markedly, when the glucose concentration was maintained at 0.15 g·L-1by using glucose-stat feeding. Finally, the glucose concentration was maintained at 0.10 g·L-1and the DO level was controlled at approximately 30% during the whole fermentation period, using the combined feeding strategy of glucose-stat feeding and DO feedback feeding. The acetate accumulation was decreased to 7.23 g·L-1, and biomass and production of L-isoleucine were increased to 46.8 and 11.95 g·L-1, respectively.
authors.affiliation: Department of Bioengineering, College of Biological and Agricultural Engineering, Jilin University, Changchun , Jilin , China.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology , Tianjin , China ; Key Laboratory of Industrial Microbiology of Education Ministry, Tianjin University of Science and Technology , Tianjin , China ; Tianjin Research Institute of Industrial Microbiology , Tianjin , China.
authors.forename: Bing
authors.initials: B
authors.lastname: Wen
authors.affiliation: National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology , Tianjin , China ; Key Laboratory of Industrial Microbiology of Education Ministry, Tianjin University of Science and Technology , Tianjin , China.
authors.forename: Qingyang
authors.initials: Q
authors.lastname: Xu
authors.affiliation: National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology , Tianjin , China ; Key Laboratory of Industrial Microbiology of Education Ministry, Tianjin University of Science and Technology , Tianjin , China.
authors.forename: Xixian
authors.initials: X
authors.lastname: Xie
authors.affiliation: National and Local United Engineering Lab of Metabolic Control Fermentation Technology, Tianjin University of Science and Technology , Tianjin , China ; Key Laboratory of Industrial Microbiology of Education Ministry, Tianjin University of Science and Technology , Tianjin , China.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
keywords: E. coli; L-isoleucine; acetate; carbon source; feeding strategy