Garrett Baird ’17


Chemical Engineering

Project Title

Nitrogen-Fixing Soil Bacteria and Their Response to Trace Elements

Presentation Link

View Garrett's Presentation

This summer I had the opportunity to study two nitrogen-fixing soil bacteria, Azotobacter Vinelandii and Azotobacter Chroococcum, and their response to trace elements such as Boron and Tungsten. I tracked the growth of the bacteria by measuring optical density. Additionally, I analyzed their siderophore production by running liquid chromatographymass spectrometry (LC-MS) samples to see which molecules the bacteria were producing in response to various concentrations of metals being added to their growth media. I found that Azotobacter Chroococcum grew better under high Tungsten concentrations than Azotobacter Vinelandii, which is unusual since Vinelandii usually grows better than Chroococcum under most conditions. Finally, I collected samples for inductively coupled plasma mass spectrometry (ICP-MS) to measure intracellular metal concentrations. This suggests that Chroococcum could be using Tungsten instead of Molybdenum in the nitrogenase responsible for converting atmospheric nitrogen into forms of nitrogen that organisms can use. This internship was a great opportunity to apply some of the skills I learned in the classroom as well as learn many new techniques and skills. It gave me valuable research experience that I will apply towards undergraduate independent work and my future career as a chemical engineer.

Internship Year


Project Category

Climate Change and Environmental Science


Morel Lab, Geosciences Department, Princeton University, Princeton, NJ


François Morel, Professor, Geosciences