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Water matrix and age effects on microorganism Raman microspectroscopy
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Paper Abstract

Raman microspectroscopy is used to probe the age and milieu parameters for suspensions of bacteria for their detection in water backgrounds. No studies have been reported on the fate of Raman signatures over time for biologicals stored in water matrices. A FALCON II Raman Chemical Imaging System (ChemImage, Pittsburgh, PA) and 532 nm laser excitation source acquired the Raman spectra. MATLAB principal components (PC) analysis software was employed for data reduction. Suspensions of Bacillus atrophaeus, Bacillus thuringiensis, and three strains of E. coli (EC) were prepared in distilled and recipe tap water. Aliquots at 5 min, 5 hr, and 1, 2, and 7 days at 25 C were dried on microscope slides in replicate. Adequate spectral differences were observed for all three organism species. Microscope analysis showed that freshly suspended Bacillus spores and EC vegetative cells, in both water matrices, remained as spores after seven days. Agar plate growth procedures showed that the bacteria were still viable even after seven days resting in both water matrices. All three bacterial species were separated based on PC analysis; however, the three EC strains coalesced. The water matrix parameter was inconsistent in its ability to separate the Raman spectra in PC plots of the five bacteria. Within each group, the time parameter poorly separated the bacterial resting suspensions as the aging proceeded. A Mahalanobis linkage distance analysis (dendrogram) for all three species and strains in both water matrices confirmed a random order for all five suspension times.

Paper Details

Date Published: 5 May 2010
PDF: 11 pages
Proc. SPIE 7665, Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XI, 766508 (5 May 2010); doi: 10.1117/12.839852
Show Author Affiliations
Ashish Tripathi, SAIC (United States)
Rabih E. Jabbour, SAIC (United States)
Patrick J. Treado, ChemImage Corp. (United States)
Matthew P. Nelson, ChemImage Corp. (United States)
A. Peter Snyder, U.S. Army Edgewood Chemical Biological Ctr. (United States)

Published in SPIE Proceedings Vol. 7665:
Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) Sensing XI
Augustus Way Fountain III; Patrick J. Gardner, Editor(s)

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