[Spectrofluorometric analysis of Escherichia coli during storage in a physiological solution]

Escherichia coli cells were kept in a physiological solution at room temperature. The fluorescence of aqueous suspensions of the cells and the medium was recorded every day. Inactivation of the culture was found to be accompanied with the appearance in the medium of protein and non-protein fluorescent metabolites. The coefficient of correlation between the quantity of living cells and the intensity of fluorescence emitted by the non-protein component had a negative sign and differed reliably from zero. The authors discuss the nature of non-protein fluorescence and what made the cells die off in the process of storage.