Research Intern / Assistant
Context
Integration into the Environmental and Molecular Microbiology team as part of an internship, counting towards both my Diplôme d’Ingénieur and my Cell-Physics Master. Study of chemotaxis in the magnetotactic bacterium Magnetospirillum gryphiswaldense MSR-1.
Goals
Determination of chemical species that trigger a chemotactic response, followed by characterization of the latter.
Approach
Several organic acids were tested to determine their ability to serve as sources of carbon and electrons for MSR-1 and thus potentially represent chemotactic attractants. Work carried out in a microbiology laboratory: handling under a laminar flow hood, use of microscopy, image processing and analysis, data extraction, modeling, and computer analysis.
Results
The results of growth curves and bacterial motility on soft agar showed that lactate, acetate, propionate, pyruvate, and succinate are responsible for the chemotactic response. In order to characterize the latter, the activity of one of the flagellar motors of several bacteria was monitored in the absence of attractants. This first step provided a reference for comparing motor activity in the presence of attractants. The results show an almost zero stopping frequency, symmetry between clockwise and counterclockwise rotation speeds, and finally a preference of the flagellar motor for counterclockwise rotation. In the long term, this study makes magnetotactic bacteria particularly interesting for the development of magnetically guided microrobots used for medical applications such as targeted drug delivery.