STEADY-STATE AND DECAY CHARACTERISTICS OF PROTEIN TRYPTOPHAN FLUORESCENCE FROM BACTERIA

The intrinsic steady-state fluorescence and fluorescence decay of Staphylococcus epidermidis, Pseudomonas fluorescens, Enterobacter cloacae, Escherichia coli, and Bacillus subtilis have been observed. Each organism exhibits a strong maximum in its emission spectrum at 330-340 nm when excited at 290 nm. Iodide quenching and denaturization experiments with 8 M urea provide strong evidence for the assignment of the 330-340-nm fluorescence to protein tryptophan. Most importantly, the decay of this bacterial protein-tryptophan fluorescence has been described by two exponential functions in all cases.