UV Raman Spectral Intensities of E. Coli and Other Bacteria Excited at 228.9, 244.0, and 248.2 nm

Abstract

Resonance Raman spectral intensities per average bacterial cell have been measured quantitatively for Gram-negative Escherichia coli, Citrobacter freundii, and Enterobacter aerogenes, as well as Gram-positive Bacillus subtilis and Staphylococcus epidermidis. Spectra have been obtained from cultures in the lag, log, and stationary growth phases excited in turn by 228.9, 244.0, and 248.2 nm light. Although Raman spectral peak positions (cm(-1)) excited by a given wavelength are very similar for all five bacterial species, the organisms are characterized by significantly different spectral intensity values. Intensity changes are associated with growth phase changes in all of the species as well. A comparison of measured with estimated average intensities has been made for spectra of log-phase E. coli. It is possible to compare measured intensities with intensities estimated for log-phase E. coli on the basis of the knowledge of its known average cellular molecular composition. A significant degree of hypochromism is observed in E. coli nucleic acid spectra. In contrast, strong average hyperchromism characterizes all aromatic amino acid peaks belonging to the same E. coli cells. Results suggest that knowledge of spectral intensity values will enhance significantly the capability to identify bacteria by means of their UV resonance Raman spectra.

Deep ultraviolet resonant Raman imaging of a cell

“…22 The method is also used for cellular level analysis: using resonance, DUV can selectively observe such aromatic compounds in a cell. [23][24][25] Cellular conditions, 26 types, 27 and metabolic states 28 have all been studied using DUV Raman, and these aromatic compounds play important roles in dynamic activities and functions of cells.…”

“…27 We chose the band at 1490 cm −1 for cellular nucleotide imaging. The distribution of the intensity at 1490 cm −1 is shown in Fig.…”

An integrated dielectrophoretic chip for continuous bioparticle filtering, focusing, sorting, trapping, and detecting

“…In contrast, a detection method that has minimal preparatory sequences and has been used for on-chip detection is spectroscopy, such as infrared ͑IR͒, ultraviolet and visible ͑UV-Vis͒ and Raman spectroscopy. [31][32][33] IR and Raman spectroscopy measure the vibrational modes of the molecules and the various structures, thus providing a detailed spectrum. 34 In particular, Raman spectroscopy can often show bonds that are undetectable through IR, thus, it has been shown to be extremely specific to each bacterium, where each spectrum can act as a fingerprint.…”

Understanding the Application of Raman Spectroscopy to the Detection of Traces of Life

“…Pioneering work by Naumann et al (1991aNaumann et al ( , 1991b showed that IR and Raman spectroscopy can be used to classify bacteria and yeasts. Using deep UV excitation (e.g., 244 nm), direct investigation of macromolecules such as DNA or proteins becomes possible due to resonant enhancement (e.g., Manoharan et al, 1990;Chadha et al, 1993;Wu et al, 2001;Jarvis and Goodacre, 2004). Storrie-Lombardi et al (2001) and Tarcea et al (2007) showed that Raman excitation wavelengths in the deep UV region are able to selectively enhance Raman signals of proteins and DNA=RNA.…”