Advanced Materials: TechConnect Briefs 2015Advanced Materials TechConnect Briefs 2015

Nanoscale Materials Characterization Chapter 1

Insight into bacteria: magnetosomes chains under photoemission electron and scanning electron microscopes

C. Keutner, A. von Bohlen, U. Berges, P. Espeter, C.M. Schneider, C. Westphal
TU Dortmund University, Germany

pp. 1 - 4

Keywords: magnetosome, electron microscopy, X-ray absorption spectroscopy, energy dispersive X-ray spectroscopy, magnetotactic bacteria

Magnetotactic bacteria (MTB) are forming magnetosome chains consisting of greigite or iron oxides. In technological, medical, and environmental applications magnetosomes are considered as perspective material. Among all techniques applied to MTB, two providing spatial, chemical, and even magnetic information are missing. These are photoemission electron microscopy (PEEM) and scanning electron microscopy with energy dispersive x-ray spectrometry (SEM-EDX). We present two methods of preparing Magnetospirillum magnetotacticum. Both yield intact bacteria with their in-vivo structure, as we will demonstrate by SEM-pictures. The first PEEM images of MTB will be shown. Further, we demonstrate that PEEM is suitable to investigate the magnetosome chains. Since each point of the entire image is acquired simultaneously and without scanning, this could become beneficial for studies of dynamic processes. These could be, for instance, the magnetosome chain's response to changing magnetic fields, since a physical realignment of the MTB is prevented by their fixed position on the surface. By applying identical preparation methods, we also report on the first SEM images in which the magnetosome chains of intact bacteria are directly visible, and we further show that single magnetosomes are distinguishable within these chains. By performing SEM-EDX measurements we are able confirm the composition of the magnetosomes.