Raman spectroscopy of Bacillus thuringiensis physiology and inactivation
National Institute of Standards and Technology, Biochemical Science Division, 100 Bureau Drive MS 8312, 20899-8310, Gaithersburg, MD, USA
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Accepted: 15 October 2012
Published online: 7 December 2012
The ability to detect spore contamination and inactivation is relevant to developing and determining decontamination strategy success for food and water safety. This study was conducted to develop a systematic comparison of nondestructive vibrational spectroscopy techniques (Surface-Enhanced Raman Spectroscopy, SERS, and normal Raman) to determine indicators of Bacillus thuringiensis physiology (spore, vegetative, outgrown, germinated and inactivated spore forms). SERS was found to provide better resolution of commonly utilized signatures of spore physiology (dipicolinic acid at 1006 cm−1 and 1387 cm−1) compared to normal Raman and native fluorescence indigenous to vegetative and outgrown cell samples was quenched in SERS experiment. New features including carotenoid pigments (Raman features at 1142 cm−1, 1512 cm−1) were identified for spore cell forms. Pronounced changes in the low frequency region (300 cm−1 to 500 cm−1) in spore spectra occurred upon germination and inactivation (with both free chlorine and by autoclaving) which is relevant to guiding decontamination and detection strategies using Raman techniques.
© Società Italiana di Fisica and Springer-Verlag Berlin Heidelberg, 2012