Open AccessTwo-Step Production of Phenylpyruvic Acid from L-Phenylalanine by Growing and Resting Cells of Engineered Escherichia coli: Process Optimization and Kinetics Modeling
Author(s) -
Ying Hou,
Gazi Sakir Hossain,
Jianghua Li,
HyunDong Shin,
Long Liu,
Guocheng Du,
Jian Chen
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0166457
Subject(s) - biotransformation , bioconversion , bioreactor , phenylpyruvic acid , phenylalanine , chemistry , escherichia coli , biochemistry , product inhibition , fermentation , chromatography , food science , enzyme , organic chemistry , non competitive inhibition , amino acid , gene
Phenylpyruvic acid (PPA) is widely used in the pharmaceutical, food, and chemical industries. Here, a two-step bioconversion process, involving growing and resting cells, was established to produce PPA from l -phenylalanine using the engineered Escherichia coli constructed previously. First, the biotransformation conditions for growing cells were optimized ( l -phenylalanine concentration 20.0 g·L −1 , temperature 35°C) and a two-stage temperature control strategy (keep 20°C for 12 h and increase the temperature to 35°C until the end of biotransformation) was performed. The biotransformation conditions for resting cells were then optimized in 3-L bioreactor and the optimized conditions were as follows: agitation speed 500 rpm, aeration rate 1.5 vvm, and l -phenylalanine concentration 30 g·L −1 . The total maximal production (mass conversion rate) reached 29.8 ± 2.1 g·L −1 (99.3%) and 75.1 ± 2.5 g·L −1 (93.9%) in the flask and 3-L bioreactor, respectively. Finally, a kinetic model was established, and it was revealed that the substrate and product inhibition were the main limiting factors for resting cell biotransformation.