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Title: Measuring spectroscopy and magnetism of extracted and intracellular magnetosomes using soft X-ray ptychography

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 (Fe 3O 4 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 resultsmore » demonstrate that spectro-ptychography offers a superior means of characterizing the chemical and magnetic properties of MTB at the individual magnetosome level.« less
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [3] ;  [6] ;  [3] ;  [3]
  1. McMaster Univ., Hamilton, ON (Canada). Dept. of Chemistry and Chemical Biology
  2. Univ. of Nevada, Las Vegas, NV (United States). School of Life Sciences
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Engineering Division
  5. Univ. Federal do Rio de Janeiro, de Janeiro (Brazil). Inst. de Microbiologia
  6. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); National Synchrotron Radiation Research Center, Hsinchu, Taiwan (Republic of China)
Publication Date:
Grant/Contract Number:
AC02-05CH11231; EAR-1423939
Type:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 113; Journal Issue: 51; Journal ID: ISSN 0027-8424
Publisher:
National Academy of Sciences, Washington, DC (United States)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Canada Foundation for Innovation; Natural Sciences and Engineering Research Council of Canada (NSERC); National Research Council (NRC); Canadian Institute for Health Research
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; ptychography; magnetotactic bacteria; biomineralization; STXM; XAS-XMCD
OSTI Identifier:
1334822
Alternate Identifier(s):
OSTI ID: 1379619