Sampling tube device for monitoring intracellular metabolite dynamics

Continuous sampling of microorganisms from a controlled bioreactor with rapid inactivation of metabolism and extraction of metabolites using precooled -40°C perchloric acid solution (35%) was achieved with a sampling tube, thus fixing fast dynamic reactions at a certain position in the tube. After sampling was stopped (200 s) the tube was frozen at -80°C and divided into identical parts and the extracted metabolites were analyzed enzymatically. A high resolution in time was achieved due to the axial dispersion of the metabolites in the sampling tube: The events of 1 s in the cells of the reactor were represented by 15 parts of the sampling tube. Axial dispersion was determined quantitatively with tracer measurements. The performance of the sampling tube device was evaluated with dynamic investigations on glucose metabolism of Zymomonas mobilis. The dynamics of intracellular glucose 6-phosphate, glyceraldehyde 3-phosphate, and 3- phosphoglycerate concentrations were monitored after adding a glucose pulse to a glucose-limited steady-state culture.