CORRELATION BETWEEN CELLULAR FLUORESCENCE AND NAD(P)H LEVELS IN ALCALIGENES-EUTROPHUS JMP-134

The culture fluorescence of Alcaligenes eutrophus JMP 134 was determin ed on-line by an Ingold Fluorosensor(TM) and correlated to the intrace llular concentrations of reduced nicotinamide adenine dinucleotide (ph osphate). The data were obtained from aerobic cultures of the strain g rowing chemostatically on phenol, phenol + sodium formate and fructose , as well as from aerobic/anaerobic transitions and substrate pulse ex periments. The total culture fluorescence was corrected to take into a ccount the inner filter effect of cells. Upon analysing the intracellu lar concentration of the dinucleotides using HPLC, it became evident t hat both NADH and NADPH contribute significantly to the fluorescence s ignal. A linear relationship between the sum of NAD(P)H and the net cu lture fluorescence was obtained from these data with a correlation fac tor of r = 0.82. These investigations indicate that the measurement of culture fluorescence is a practicable tool for monitoring the redox s tate of a cellular culture, provided the total fluorescence signal is adjusted and the investigations are supported by direct measurements o f intracellular levels of reduced dinucleotides.