Rapid characterization of microorganisms by UV-resonance Raman and fluorescence spectroscopy

Mi-Ok Park Baek, University of Rhode Island

Abstract

Fluorescence emission-excitation spectra or fluorescence decay kinetics have been examined for seventeen marine plankton algae from seven classes and ten genera. The strongest primary fluorescence which occurred in the 320-340 nm range when excited at 290 nm was attributed to protein tryptophan. Protein tryptophan lifetimes were characteristic for different species of algae but varied over a small range of lifetime values. Greater differences between species were found in fluorescence emissions, tentatively assigned to pteridine derivatives and phycoerythrin, which show much more characteristic lifetimes as well. However, sensitivities are somewhat lower than for tryptophan. Results show that fluorescence emission and excitation spectra coupled with lifetime data may be useful in characterizing algae and that algal fluorescence is very different from bacterial fluorescence.^ UV resonance Raman spectra of algae show that with 222.5, 230.6, and 242.4 nm excitation only very weak peaks due to protein and possibly nucleic acids are present. In contrast, very strong spectra of quinones are observed with 251.0 nm excitation. Algae Raman spectra are very different from bacterial spectra.^ UV resonance Raman spectra of native lysozyme excited at 230.6 nm show strong protein tryptophan, tyrosine, and proline peaks which appear to be sensitive to the protein secondary and tertiary structure since the heating of the protein causes substantial shifts in Raman peak positions. Very similar changes occur in S. epidermidis spectra when the bacteria are subject to heating at 60$\sp\circ$C for 30 minutes. Such changes should allow easy identification of heat-killed bacteria. ^

Subject Area

Chemistry, Inorganic

Recommended Citation

Mi-Ok Park Baek, "Rapid characterization of microorganisms by UV-resonance Raman and fluorescence spectroscopy" (1987). Dissertations and Master's Theses (Campus Access). Paper AAI8811549.
http://digitalcommons.uri.edu/dissertations/AAI8811549

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