Time-resolved fluorescence spectra have been obtained for Escherichia coli, Pseudomonas fluorescens, Staphylococcus epidermidis, and Enterobacter cloacae. Pseudomonas fluorescens has been shown to have distinctly different time-resolved spectra. Fluorescence excitation spectra for the three other organisms showing similar time-resolved spectra are very nearly alike, while spectra of Pseudomonas fluorescens are markedly different. This suggests that the changes in the average fluorescence lifetime with emission wavelength are due to the separate contributions from fluorophores of distinctly different lifetimes which have emission maxima at different wavelengths.
