Isabella Marshall

“Rhizosphere-on-a-chip for Microbiome Studies”

Project Summary:

The rhizosphere of a plant is an elusive soil ecosystem comprised of bacteria, fungi, and viruses that surround plant roots. The major barrier to studying rhizosphere microbiota is the inability to grow the organisms in current laboratory settings, which involve culturing on solid or liquid media. Since over 95% of soil bacteria are unable to grow under these laboratory conditions, new methods of microbial cultivation that better simulate rhizosphere conditions are needed. The objective of this project was to develop a new platform to study rhizosphere bacteria using electroactivity data collected from a fabricated system. We designed and fabricated a four-electrode system to evaluate bacteria samples. Escherichia coli, Bacillus subtilis, and Streptomyces sp. were tested at different concentrations. To measure the bacteria’s conductivity, voltage was applied across the sample, and the resulting current was recorded. MATLAB code was used to gather data from the source meter to perform these measurements. Conductivity readings of bacterial concentrations ranging from 1x to 1000x were plotted against the colony-forming units (CFU) of each bacteria. Across all three species, a linear correlation was found between the voltage current and the bacterial CFU, implying an ability to detect bacterial abundance in environmental samples using electroactivity. Future directions involve using soil extractions to simulate a soil environment to detect microbial activity. The portability and miniature size of the technology show great promise in being developed for in-situ field studies of soil microbial activity, which is a key component of soil health.

My Experience:

My experiences this summer allowed me to explore interdisciplinary research across Electrical and Computer Engineering and Biology that I otherwise would not be exposed to. My knowledge of the research process greatly improved as well as my laboratory skills. I was introduced to new lab methods as well as new machinery and software. In addition to all that I learned, I had great support from my research mentors. I look forward to what comes next in my research path.