Simple and robust method for estimation of the split between the oxidativepentose phosphate pathway and the Embden-Meyerhof-Parnas pathway in microorganisms

The flux through the oxidative pentose phosphate (PP) pathway was estimated in Bacillus clausii, Saccharomyces cerevisiae, and Penicillium chrysogenum growing in chemostats with [1-C-13]glucose as the limiting substrate. The flux calculations were based on a simple algebraic expression that is valid irrespective of isotope rearrangements arising from reversibilities of the reactions in the PP pathway and the upper part of the Embden-Meyerhof-Parn as pathway. The algebraically calculated fluxes were validated by comparing the results with estimates obtained using a numerical method that includes the entire central carbon metabolism. Setting the glucose uptake rate to 1 00, the algebraic expression yielded estimates of the PP pathway flux in B. clausii, S. cerevisiae, and P. chrysogenum of 20, 42, and 75, respectively . These results are in accordance with the results from the numerical metho d. The information on the labeling patterns of glucose and the proteinogeni c amino acids were obtained using gas chromatography/mass spectrometry, whi ch is a very sensitive technique, and therefore only a small amount of biom ass is needed for the analysis. Furthermore, the method developed in this s tudy is fast and readily accessible, as the calculations are based on a sim ple algebraic expression. (C) 2001 John Wiley & Sons, Inc. Biotechnol Bioen g 74: 517-523, 2001.