Examining the chemistry and magnetism of magnetotactic bacterium Candidatus Magnetovibrio blakemorei strain MV-1 using scanning transmission X-ray microscopy

摘要

Scanning transmission X-ray microscopy (STXM) measurements at the CK, O K and Fe L _3 edges were used to study the magnetotactic bacterium Candidatus Magnetovibrio blakemorei strain MV-1 on an individual cell basis. Improved data acquisition methodologies resulting in higher quality results are presented. Visualization of magnetosomes from their O K-edge signal is demonstrated. The Fe L _3 X-ray magnetic circular dichroism (XMCD) signal was used to characterize the magnetic properties of several MV-1 cells on an individual magnetosome basis. The absolute magnetic moment from two cells was evaluated and found to be 0.93(6) of that of saturated abiotic magnetite, or 3.6(2) μB. Previously observed excess Fe (II) was not found in this study, suggesting the prior observation (Lam et al., Chem. Geol 270 (2010) 110) may have been a radiation damage artifact.