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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 17, Iss. 19 — Sep. 14, 2009
  • pp: 16480–16491

Characterization of single heat-activated Bacillus spores using laser tweezers Raman spectroscopy

Pengfei Zhang, Peter Setlow, and Yongqing Li  »View Author Affiliations

Optics Express, Vol. 17, Issue 19, pp. 16480-16491 (2009)

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Heat activation of dormant bacterial spores is a short treatment at a sublethal temperature that potentiates and synchronizes spore germination. In this paper, laser tweezers Raman spectroscopy (LTRS) was used to study the heat activation of single spores of Bacillus cereus and Bacillus subtilis. We measured the Raman spectra of single spores without treatment, during heat activation at 65 °C (B. cereus) or 70 °C (B. subtilis), and following heat activation and cooling to 25 °C. Principle component analysis (PCA) was applied to discriminate among the three groups of spores based on their Raman spectra. The results indicated that: (1) there are large changes in the Raman bands of Ca-DPA and protein for both B. cereus and B. subtilis spores during heat activation, indicative of changes in spore core state and partial protein denaturation at the heat activation temperatures; (2) these spectral changes become smaller once the heated spores are cooled, consistent with heat activation being reversible; (3) minor spectral differences between untreated and heat-activated and cooled spores can be discriminated by PCA based on non-polarized and polarized Raman spectra; and (4) analysis based on polarized Raman spectra reveals that partial denaturation of protein during heat activation is mainly observed in the vertically polarized component.

© 2009 OSA

OCIS Codes
(170.1530) Medical optics and biotechnology : Cell analysis
(170.5660) Medical optics and biotechnology : Raman spectroscopy

ToC Category:
Medical Optics and Biotechnology

Original Manuscript: June 11, 2009
Revised Manuscript: July 22, 2009
Manuscript Accepted: July 23, 2009
Published: September 1, 2009

Virtual Issues
Vol. 4, Iss. 11 Virtual Journal for Biomedical Optics

Pengfei Zhang, Peter Setlow, and Yongqing Li, "Characterization of single heat-activated Bacillus spores using laser tweezers 
Raman spectroscopy," Opt. Express 17, 16480-16491 (2009)

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