Multicellularity makes the difference: multicellular magnetotactic prokaryotes have dynamic motion parameters dependent on the magnetic field intensity

Abstract

Magnetotactic microorganisms can be found as unicellular entities, as coccus, vibrios, spirilla, rods and protists as well as multicellular organisms. The most studied multicellular magnetotactic prokaryote is “Candidatus Magnetoglobus multicellularis,” composed by an average number of 17 genetically identical magnetotactic bacteria. It is known that the magnetotactic orientation of “Ca. M. multicellularis” is different from the orientation shown by uncultured magnetotactic cocci. The present manuscript has the aim to compare the dynamic parameters of motion of both the magnetotactic microorganisms. U-turns trajectories were recorded, and one branch of the turn was used to get the trajectory parameters. The individual magnetic moment was estimated using the U-turn diameter. The parameters analyzed were the rotational drag coefficient, the kinetic energy, the flagellar force and the flagellar output power. From the rotational drag coefficient analysis, it was observed a difference among the experimental value and the expected value, and an “effective radius” is proposed to explain that difference. It was observed for the uncultured magnetotactic cocci that the kinetic energy, flagellar force and flagellar power are independent of the magnetic field intensity but for “Ca. M. multicellularis” an increase in these values was observed with the magnetic field intensification. It is proposed that the distribution of magnetic moments around the body of “Ca. M. multicellularis” is responsible for some magnetic force acting on its body in the presence of a uniform magnetic field. Also, the dynamic motion parameters calculated must support studies on the dynamic of motion of microorganisms.