The in-situ infrared microspectroscopy of bacterial colonies on agar plates

• Main Author: Sang, Shu-Chih
• Other Authors: Ball State University. Dept. of Chemistry.
• Format: Others
• Published: 2011
• Subjects: Bacteria > Identification.; Fourier transform spectroscopy.; Spectrum analysis.
• Online Access: http://cardinalscholar.bsu.edu/handle/handle/185674; http://liblink.bsu.edu/uhtbin/catkey/1014855

The purpose of this research was to develop a more convenient method to distinguish bacteria using Fourier transform infrared (FT-IR) spectroscopy. The specular reflectance infrared spectra of bacterial colonies were obtained in-situ, without removing them from the agar growth media. The spectra of a variety of bacterial species were obtained by the infrared microscope and then were analyzed by factor analysis. Using this statistical method in conjunction with in-situ sampling we evaluated how well Grampositive species were sorted from Gram-negative species. Also, how the type of agar used and how the age of bacterial colonies affects the results of Gram stain predictions were evaluated; our experiments showed that the influence of those various conditions can be decreased. The suitability of various sets of standard spectra for predicting Gram stain, including sets constructed with and without Kramers-Kronig transformation and those constructed using partial regions verses the complete mid-infrared region, was evaluated.The effect that water on the surface of the colonies has been studied in distinguishing bacteria. Furthermore, the original method was improved and the method's suitability to differentiate a larger number of different bacterial species was examined. === Department of Chemistry