Journal
METABOLIC ENGINEERING
Volume 32, Issue -, Pages 184-194Publisher
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.ymben.2015.09.017
Keywords
Biosensor; Adaptive laboratory evolution; Transcription factor; Cotynebacterium glutamicum; L-valine; Metabolic engineering
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Funding
- German Federal Ministry of Education and Research (BMBF OptoSys grant) [031A167B]
- Helmholtz Association (Helmholtz YIG) [VH-NG-716]
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Adaptive laboratory evolution has proven a valuable strategy for metabolic engineering. Here, we established an experimental evolution approach for improving microbial metabolite production by imposing an artificial selective pressure on the fluorescent output of a biosensor using fluorescence-activated cell sorting. Cells showing the highest fluorescent output were iteratively isolated and (re-) cultivated. The L-valine producer Corynebacterium glutamicum Delta aceE was equipped with an L-valine-responsive sensor based on the transcriptional regulator Lrp of C. glutamicum. Evolved strains featured a significantly higher growth rate, increased L-valine titers (similar to 25%) and a 3-4-fold reduction of by-product formation. Genome sequencing resulted in the identification of a loss-of-function mutation (UreD-E188*) in the gene ureD (urease accessory protein), which was shown to increase L-valine production by up to 100%. Furthermore, decreased L-alanine formation was attributed to a mutation in the global regulator GlxR. These results emphasize biosensor-driven evolution as a straightforward approach to improve growth and productivity of microbial production strains. (C) 2015 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.
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