VARIABILITY OF STEADY-STATE BACTERIAL FLUORESCENCE WITH RESPECT TO GROWTH-CONDITIONS

The UV-excited (approximately 280 nm) fluorescence emission spectra fr om suspensions of several different species of bacteria are examined t o determine to what extent differences in condition of growth change t heir spectra. This is an important factor if these spectra are conside red for use for identification of species. It was found that the spect ra were relatively invariant with respect to whether the bacteria were harvested during growth (log phase) or after the medium was depleted (stationary phase). For a given strain of Escherichia coli it was foun d that the emission spectrum did not change for growth in rich, compar ed to minimal, medium; however, there was some change for other specie s. For bacterial spores, the emission spectra were found to be similar for several species. An estimate was made for the quantum yield for B acillus megaterium spores. The emission spectrum from spores and bacte ria was found to change substantially on drying.