Improving acetate tolerance of Escherichia coli by rewiring its global regulator cAMP receptor protein (CRP)

PLoS One. 2013 Oct 4;8(10):e77422. doi: 10.1371/journal.pone.0077422. eCollection 2013.

Abstract

The presence of acetate exceeding 5 g/L is a major concern during E. coli fermentation due to its inhibitory effect on cell growth, thereby limiting high-density cell culture and recombinant protein production. Hence, engineered E. coli strains with enhanced acetate tolerance would be valuable for these bioprocesses. In this work, the acetate tolerance of E. coli was much improved by rewiring its global regulator cAMP receptor protein (CRP), which is reported to regulate 444 genes. Error-prone PCR method was employed to modify crp and the mutagenesis libraries (~3×10(6)) were subjected to M9 minimal medium supplemented with 5-10 g/L sodium acetate for selection. Mutant A2 (D138Y) was isolated and its growth rate in 15 g/L sodium acetate was found to be 0.083 h(-1), much higher than that of the control (0.016 h(-1)). Real-time PCR analysis via OpenArray(®) system revealed that over 400 CRP-regulated genes were differentially expressed in A2 with or without acetate stress, including those involved in the TCA cycle, phosphotransferase system, etc. Eight genes were chosen for overexpression and the overexpression of uxaB was found to lead to E. coli acetate sensitivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetates / pharmacology*
  • Cyclic AMP Receptor Protein / genetics
  • Cyclic AMP Receptor Protein / metabolism*
  • Escherichia coli / drug effects*
  • Escherichia coli / physiology*
  • Fermentation
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial
  • Mutation
  • Salt Tolerance* / genetics
  • Stress, Physiological / genetics

Substances

  • Acetates
  • Cyclic AMP Receptor Protein

Grants and funding

This project is supported by Ministry of Education, Singapore (RG27/11) and Life Technologies CRC program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.