Frontiers in Microbiology (Aug 2019)

Continuous Adaptive Evolution of a Fast-Growing Corynebacterium glutamicum Strain Independent of Protocatechuate

  • Michaela Graf,
  • Thorsten Haas,
  • Felix Müller,
  • Anina Buchmann,
  • Julia Harm-Bekbenbetova,
  • Andreas Freund,
  • Alexander Nieß,
  • Marcus Persicke,
  • Jörn Kalinowski,
  • Bastian Blombach,
  • Bastian Blombach,
  • Ralf Takors

DOI
https://doi.org/10.3389/fmicb.2019.01648
Journal volume & issue
Vol. 10

Abstract

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Corynebacterium glutamicum is a commonly applied host for the industrial production of amino acids. While valued for its robustness, it is somewhat inferior to competing strains such as Escherichia coli because of the relatively low growth rate of 0.40 h−1 in synthetic, industrial media. Accordingly, adaptive laboratory evolution (ALE) experiments were performed in continuous cultivation mode to select for a growth-improved host. To ensure industrial attractiveness, this ALE study aimed at a reduction of dependency on costly growth-boosting additives such as protocatechuate (PCA) or complex media supplements. Consequently, double selection pressures were installed consisting of a steady increase in growth rate demands and a parallel reduction of complex medium fractions. Selection yielded C. glutamicum EVO5 achieving 0.54 h−1 and 1.03 gGlc gCDW−1 h−1 in minimal medium without abovementioned supplements. Sequencing revealed 10 prominent mutations, three of them in key regulator genes.

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