Use of NAD(P)H-fluorescence for monitoring the response of starved cells of Catharanthus roseus in suspension to metabolic perturbations

In this investigation we have measured, on-line, the concentration of NAD(P)H of a quasi-steady state culture of Catharanthus roseus subjected to a variety of different metabolic perturbations, including transition from aerobic to anaerobic conditions, and glucose pulse feeding. The NAD(P)H fluorescence was found to qualitatively represent the metabolic state of cells during substrate perturbation. NAD(P)H fluorescence increased immediately upon aerobic-anaerobic transition and decreased immediately after returning to aerobic conditions. NAD(P)H fluorescence response following a decrease or increase in dissolved oxygen tension indicates that the cells are in an aerobic (or oxidized) state at as low an oxygen tension as 11% air saturation.