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Control Characteristics of Magnetotactic Bacteria: <italic>Magnetospirillum Magnetotacticum</italic> Strain MS-1 and <italic>Magnetospirillum Magneticum</italic> Strain AMB-1

2013; IEEE Magnetics Society; Volume: 50; Issue: 4 Linguagem: Inglês

10.1109/tmag.2013.2287495

1941-0069

Islam S. M. Khalil, Sarthak Misra,

Magnetic and Electromagnetic Effects

Magnetotactic bacteria have the potential to execute nontrivial tasks, such as microactuation, micromanipulation, and microassembly, under the influence of the controlled magnetic fields. Closed-loop control characteristics of these magnetic microorganisms depend on their self-propulsion forces (motility) and magnetic dipole moments. These properties can be controlled through the growth conditions of magnetotactic bacteria. We provide a comparison between two species of magnetotactic bacteria, i.e., Magnetospirillum magnetotacticum strain MS-1 and Magnetospirillum magneticum strain AMB-1. This comparison includes the characterization of their morphologies, magnetic dipole moments, and closed-loop control characteristics in the transient and steady states. The characterized average magnetic dipole moments of motile cells of M. magnetotacticum and M. magneticum strains are 1.4 × 10 -16 A.m 2 and 1.5 × 10 -17 A.m 2 at a magnetic field of 7.9 mT, respectively. These magnetic dipole moments are used in the realization of closed-loop control systems for each bacterial strain. The closed-loop control systems achieve point-to-point positioning of M. magnetotacticum cells at an average velocity of 32 ± 10 μm/s (approximately seven body lengths per second), and within an average region of convergence of 23 ± 10 μm (approximately four body lengths), while cells of M. magneticum strain are positioned at an average velocity of 30 ± 12 μm/s (approximately eight body lengths per second), and within an average region of convergence of 35 ± 14 μm (approximately 14 body lengths). These results suggest that the cells of M. magnetotacticum strain have a slightly greater tendency to provide desirable closed-loop control characteristics than cells of M. magneticum strain.