High-Wavenumber Raman Spectroscopy for the Identification and Biochemical Characterization of Microbial Species

High Resolution Image Download MS PowerPoint Slide Raman spectroscopy is a powerful tool for microbiological and infectious disease research, enabling rapid discrimination of microbial species. While spectral discrimination has typically been performed using the fingerprint region (400–1800 cm –1 ), high autofluorescence backgrounds can degrade signal quality and decrease the overall effectiveness. This work investigates the effectiveness of utilizing the low-background high-wavenumber region (2800–3800 cm –1 ) to both identify and biochemically characterize microbial species. High-wavenumber spectra of 14 microbial species were collected and used to train and validate a multitiered classification model capable of identifying cell wall type (100%), genus (98.9%), and species (97.4%) with high accuracy. Additionally, utilizing a spectral unmixing approach, the relative Raman contributions from proteins, carbohydrates, nucleic acids, lipids, and cell wall components were determined for each species, with general trends matching reported physiological differences. Utilizing a method of converting high-wavenumber Raman spectral fractions to relative dry mass, a biochemical characterization of each species was obtained, with the Raman dry mass characterization of Escherichia coli ( E. coli ) closely matching previously reported values. Taken together, these results demonstrate that high-wavenumber Raman spectroscopy is a feature-rich technique capable of performing both accurate discrimination and nondestructive biochemical characterization of microbial species.