Abstract
l-tryptophan is an essential amino acid of high industrial interest that is routinely produced by microbial processes from glucose as carbon source. Glycerol is an alternative substrate providing a variety of economic and metabolic advantages. Process performance of the recombinant l-tryptophan producer Escherichia coli NT367 was studied in controlled fed-batch processes. The chromosome of the recombinant l-tryptophan producer was equipped with additional genes coding for enzymes of the aromatic amino acids biosynthetic pathway and l-serine biosynthesis, including genes for feedback-resistant enzyme variants (trpE fbr, aroFBL, and serA fbr), deletions of enzymatic steps for the degradation of precursors or the product l-tryptophan (sdaB and tnaA), and alterations in the regulation of l-tryptophan metabolism (deletion of trpL and trpR). The impact of glycerol supply rates as well as the application of a multicopy plasmid (pF112- aroFBL -kan) were investigated in fully controlled stirred-tank bioreactors on a 15 L scale. The combination of E. coli NT367 carrying pF112- aroFBL -kan and an appropriate biomass-specific glycerol supply-rate resulted in the highest final product concentration of 12.5 g L −1 l-tryptophan with the lowest concentrations of other aromatic amino acids. Fed-batch production of l-tryptophan from glycerol was shown for the first time with recombinant E. coli.
Original language | English |
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Pages (from-to) | 2881-2892 |
Number of pages | 12 |
Journal | Biotechnology and Bioengineering |
Volume | 115 |
Issue number | 12 |
DOIs | |
State | Published - Dec 2018 |
Keywords
- Escherichia coli
- fed-batch process
- glycerol
- l-tryptophan
- plasmid