Measuring spectroscopy and magnetism of extracted and intracellular magnetosomes using soft X-ray ptychography
- Department of Chemistry and Chemical Biology, McMaster University, Hamilton, ON, Canada L8S 4M1,
- School of Life Sciences, University of Nevada at Las Vegas, Las Vegas, NV 89154,
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
- Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,
- Instituto de Microbiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 2194-590, Brazil,
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720,, National Synchrotron Radiation Research Center, Hsinchu, Taiwan 30076, Republic of China
Characterizing the chemistry and magnetism of magnetotactic bacteria (MTB) is an important aspect of understanding the biomineralization mechanism and function of the chains of magnetosomes (Fe3O4 nanoparticles) found in such species. Images and X-ray absorption spectra (XAS) of magnetosomes extracted from, and magnetosomes in, whole Magnetovibrio blakemorei strain MV-1 cells have been recorded using soft X-ray ptychography at the Fe 2p edge. A spatial resolution of 7 nm is demonstrated. Precursor-like and immature magnetosome phases in a whole MV-1 cell were visualized, and their Fe 2p spectra were measured. Based on these results, a model for the pathway of magnetosome biomineralization for MV-1 is proposed. Fe 2p X-ray magnetic circular dichroism (XMCD) spectra have been derived from ptychography image sequences recorded using left and right circular polarization. The shape of the XAS and XMCD signals in the ptychographic absorption spectra of both sample types is identical to the shape and signals measured with conventional bright-field scanning transmission X-ray microscope. A weaker and inverted XMCD signal was observed in the ptychographic phase spectra of the extracted magnetosomes. The XMCD ptychographic phase spectrum of the intracellular magnetosomes differed from the ptychographic phase spectrum of the extracted magnetosomes. Lastly, these results demonstrate that spectro-ptychography offers a superior means of characterizing the chemical and magnetic properties of MTB at the individual magnetosome level.
- Research Organization:
- Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); Canada Foundation for Innovation; Natural Sciences and Engineering Research Council of Canada (NSERC); National Research Council (NRC); Canadian Institute for Health Research
- Grant/Contract Number:
- AC02-05CH11231; EAR-1423939
- OSTI ID:
- 1334822
- Alternate ID(s):
- OSTI ID: 1379619
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 113 Journal Issue: 51; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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