title: Enhancement of L-phenylalanine production by engineered Escherichia coli using phased exponential L-tyrosine feeding combined with nitrogen source optimization.
abstract: Nitrogen source optimization combined with phased exponential L-tyrosine feeding was employed to enhance L-phenylalanine production by a tyrosine-auxotroph strain, Escherichia coli YP1617. The absence of (NH4)2SO4, the use of corn steep powder and yeast extract as composite organic nitrogen source were more suitable for cell growth and L-phenylalanine production. Moreover, the optimal initial L-tyrosine level was 0.3 g L(-1) and exponential L-tyrosine feeding slightly improved L-phenylalanine production. Nerveless, L-phenylalanine production was greatly enhanced by a strategy of phased exponential L-tyrosine feeding, where exponential feeding was started at the set specific growth rate of 0.08, 0.05, and 0.02 h(-1) after 12, 32, and 52 h, respectively. Compared with exponential L-tyrosine feeding at the set specific growth rate of 0.08 h(-1), the developed strategy obtained a 15.33% increase in L-phenylalanine production (L-phenylalanine of 56.20 g L(-1)) and a 45.28% decrease in L-tyrosine supplementation.
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China.
authors.forename: Peipei
authors.initials: P
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China.
authors.forename: Weijia
authors.initials: W
authors.lastname: Cao
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China. Electronic address: kqchen@njtech.edu.cn.
authors.forename: Kequan
authors.initials: K
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: State Key Laboratory of Materials-Oriented Chemical Engineering, College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing 211816, People's Republic of China.
authors.forename: Pingkai
authors.initials: P
authors.lastname: Ouyang
mesh_terms: D061249:Batch Cell Culture Techniques; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism* / Q000494:pharmacology; D010649:Phenylalanine / Q000096:biosynthesis*; D014443:Tyrosine / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D014443:Tyrosine; D010649:Phenylalanine; D009584:Nitrogen
keywords: Engineered Escherichia coli; Fed-batch; Nitrogen source; l-Phenylalanine; l-Tyrosine feeding