Variations in the Hydrodynamic Motility of Magnetotactic Bacteria *

Magnetotactic Bacteria (MTB) are a class of bacteria which produce magnetosomes, or lipid-bound magnetic particles. Fascination with these organisms has overlapped different disciplines of science, with numerous intersections in research between physics, biology, and chemistry.  Being a motile active (living) micro-organism with innate magnetic properties, these bacteria offer novel opportunities to probe their hydrodynamics in different environments. In particular, we present preliminary results aimed at understanding the role of phenotypic characteristics in genetically identical MTB on their swimming polarity and velocity in different environments.  Weak external magnetic fields from a miniature 3-axis electromagnet system is used to control their motility and to determine the bacterial magnetic moments and speeds. The variations in bacterial environments are achieved through combination of unique ratios of autotrophic and magnetic spirillum growth media. The influence of these environments on their dynamics, as well as the role of diversity that may lead to the emergence of differing phenotypes in the studied MTB populations will be discussed.