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N Biotechnol. 2019 Mar 25;49:120-128. doi: 10.1016/j.nbt.2018.10.004. Epub 2018 Oct 29.

Effect of amino acids on transcription and translation of key genes in E. coli K and B grown at a steady state in minimal medium.

Author information

1
Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla (BUAP), Puebla 72000, Mexico. Electronic address: antonino.baez@correo.buap.mx.
2
Biotechnology Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MD, 20892, United States.
3
Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MD, 20892, United States.
4
Biotechnology Core Laboratory, National Institute of Diabetes and Digestive and Kidney Diseases, National Institute of Health, Bethesda, MD, 20892, United States. Electronic address: josephs@niddk.nih.gov.

Abstract

Growing E. coli to high densities is a common strategy for biologicals production. The process is implemented by using complex or minimal media with different feeding strategies. To understand the effect of amino acids, E. coli B and K were grown at a steady state of 0.35 h-1 in glucose minimal medium with and without amino acids, while their metabolism, protein abundance and gene expression were compared. The results showed that amino acids promoted higher acetate excretion, higher fatty acid biosynthesis (K strain), repressed glucose uptake rate, and decreased expression of proteins associated with the TCA cycle, glyoxylate shunt and amino acid biosynthesis. In presence of amino acids, E. coli K upregulated fatty acid biosynthesis and repressed more genes and proteins involved in amino acid biosynthesis than E. coli B. These findings are correlated with higher yield on glucose (Yx/s) and high specific biomass production rate (qx) in K strain in the presence of amino acids. In contrast, pre-formed precursor molecules such as amino acids did not affect fatty acid biosynthesis in E. coli B or Yx/s and qx, which were higher than those of E. coli K, suggesting that constitutive synthesis of energetically demanding precursors and higher fatty acid β-oxidation activity is key for high biomass-performer E. coli B. Both strains turned off unnecessary pathways and directed their metabolism to proteome efficient overflow metabolism likely to generate energy and provide protein to functions supporting higher growth rate.

KEYWORDS:

Chemostat; Escherichia coli; Overflow metabolism; Proteome; Transcriptome

PMID:
30385399
DOI:
10.1016/j.nbt.2018.10.004
[Indexed for MEDLINE]

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