On-Line Detection of Substrate Exhaustion by Using NAD(P)H Fluorescence.

In this study we examined the utility of NAD(P)H fluorescence for monitoring aerobic fermentations of the threonine auxotroph Corynebacterium glutamicum ATCC 14296. Instead of attempting complicated mathematical corrections for inner-filter effects, we found that it is possible to use the information contained in the on-line NAD(P)H fluorescence signal to assess culture metabolic activities during fermentation. The first derivative of the filtered fluorescence signal, which approximates the turnover rate of the NAD(P)H pool, can be used to precisely identify the temporal points of threonine and glucose exhaustion.