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Proceedings Paper

Discrimination of bacterial strains by Fourier-transform near-infrared spectroscopy using an aluminum oxide membrane
Author(s): Luis E. Rodriguez-Saona; Farukh M. Khambaty; Francis S. Fry; Elizabeth M. Calvey
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Paper Abstract

To address the need for a fast and sensitive method for the detection of bacterial contamination in solutions, the use of Fourier-transform near infrared (FT-NIR) spectroscopy and multivariate pattern recognition techniques was evaluated. The complex cellular composition of bacteria yields FT-NIR vibrational transitions (overtone and combination bands) that might be useful for identification and sub-typing. Bacteria including strains of Escherichia coli spp., Pseudomonas aeruginosa, Bacillus spp. and Listeria innocua were evaluated. The harvested cells were treated with ethanol (70% v/v) to reduce the safety concerns when evaluating pathogenic strains. The bacterial cells were concentrated on an aluminum oxide membrane to obtain a thin bacterial film. Spectra were collected by FT-NIR by using a diffuse reflection-integrating sphere. This simple membrane filtration procedure generated reproducible FT-NIR spectra that can be used for rapid discrimination among closely related strains. Principal Component Analysis (PCA) of transformed spectra in the 5000-4000 cm-1 region exhibited clusters that discriminated between bacteria species at levels < 1 mg wet cells weight (approximately 106-107 CFU/mg). Variations in the growth conditions of the bacteria substantially affected the FT-NIR spectra and diminished the ability of PCA to differentiate among strains; this underscores the importance of developing robust sampling protocols. FT-NIR in conjunction with multivariate techniques can be used for the rapid and accurate evaluation of potential bacterial contamination in liquids with minimal sample manipulation.

Paper Details

Date Published: 7 February 2002
PDF: 11 pages
Proc. SPIE 4574, Instrumentation for Air Pollution and Global Atmospheric Monitoring, (7 February 2002); doi: 10.1117/12.455148
Show Author Affiliations
Luis E. Rodriguez-Saona, Univ. of Maryland/College Park (United States)
Farukh M. Khambaty, Food and Drug Administration (United States)
Francis S. Fry, Food and Drug Administration (United States)
Elizabeth M. Calvey, Food and Drug Administration (United States)


Published in SPIE Proceedings Vol. 4574:
Instrumentation for Air Pollution and Global Atmospheric Monitoring
James O. Jensen; Robert L. Spellicy, Editor(s)

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