Elimination of GlnKAmtB affects serine biosynthesis and improves growth and stress tolerance of Escherichia coli under nutrient-rich conditions

Romina Frare, Margarita Stritzler, Cecilia Pascuan, Karen Liebrenz, Luisa Galindo-Sotomonte, Gabriela Soto, Pablo Ivan Nikel, Nicolás Ayub*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Nitrogen is a most important nutrient resource for Escherichia coli and other bacteria that harbor the glnKamtB operon, a high-affinity ammonium uptake system highly interconnected with cellular metabolism. Although this system confers an advantage to bacteria when growing under nitrogen-limiting conditions, little is known about the impact of these genes on microbial fitness under nutrient-rich conditions. Here, the genetically tractable E. coli BW25113 strain and its glnKamtB-null mutant (JW0441) were used to analyze the impact of GlnK-AmtB on growth rates and oxidative stress tolerance. Strain JW0441 showed a shorter initial lag phase, higher growth rate, higher citrate synthase activity, higher oxidative stress tolerance and lower expression of serA than strain BW25113 under nutrient-rich conditions, suggesting a fitness cost to increase metabolic plasticity associated with serine metabolism. The overexpression of serA in strain JW0441 resulted in a decreased growth rate and stress tolerance in nutrient-rich conditions similar to that of strain BW25113, suggesting that the negative influence on bacterial fitness imposed by GlnK-AmtB can be traced to the control of serine biosynthesis. Finally, we discuss the potential applications of glnKamtB mutants in bioproduction processes.
Original languageEnglish
Article numberfnaa197
JournalFEMS Microbiology Letters
Volume367
Issue number23
ISSN0378-1097
DOIs
Publication statusPublished - 2020

Keywords

  • Evolutionary innovation
  • Ammonium uptake
  • Lag phase
  • Growth rate
  • Oxidative stress

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