Glycogen metabolism in aerobic mixed cultures

In this study, the metabolism of glycogen storage and consumption in mixed cultures under aerobic conditions is described. The experimental results ar e used to calibrate a metabolic model, which as sole stoichiometric variabl es has the efficiency of oxidative phosphorylation (delta) and maintenance requirement in units of adenosine triphosphate (m(ATP)). Using the experime ntal data and values from the literature we show that delta and m(ATP) are strongly coupled and that the values determined for glycogen and poly-beta -hydroxybutyrate (PHB) metabolism are similar. We also demonstrate that sto rage of glycogen and subsequent growth occur without significant loss of en ergy, as compared with direct growth on glucose. For kinetic modeling, Mono d kinetics is used most commonly in activated sludge models to describe the rate of microbial transformation. Monod kinetics, however, does not provid e a good description of the data obtained. Second-order kinetics gives a be tter description of the rate of glycogen degradation. Formation and consump tion of glycogen appears to be much faster than for PHB. (C) 2001 John Wile y & Sons, Inc.