Master Thesis 2023 – Investigating the Effects of Environmental Stress on E. Coli Metabolism and Isotopic Signatures


Understanding the metabolic responses of microorganisms to environmental stressors is crucial in microbial ecology. Recent studies have highlighted the potential of measuring isotopic signatures, particularly δ18O(PO43-), as indicators of metabolic changes in microbial communities. Here we see a need to investigate the effects of specific stressors on the metabolic pathways and isotopic signatures of model organisms, such as Escherichia coli (E. coli), under controlled laboratory conditions.

Project work

The aim of this master’s thesis is to examine the effects of environmental stressors on E. coli metabolism and its impact on isotopic signature of phosphate. The research will focus on comparing two or three specific growing conditions to assess the metabolic responses of E. coli under various stressors. The project involves growing the bacteria, extracting phosphate, and preparing it for isotopic analysis.


  • Conduct a literature review on microbial responses to environmental stress and the metabolic pathways of E. coli.
  • Design and perform growth experiments with E. coli under specific stress conditions, such as temperature shifts or nutrient limitations.
  • Monitor and quantify the growth dynamics of E. coli using appropriate analytical techniques.
  • Collect samples, perform extractions, and prepare cytosolic phosphate for analysis.
  • Collaborate with experts to conduct isotopic analysis, such as Isotope Ratio Mass Spectrometry (IRMS) and High Resolution Mass Spectrometry (HRMS).
  • and compare the metabolic responses of E. coli under different stress conditions.

(The scope of the project can be adapted based on a bachelor or master thesis)



Website of the project: https://sae.ethz.ch/people/AssociatedStudents/elena-evertz.html