Mathematical description of microbiological reactions involving intermediates

Stoichiometric relationships for biological reactions involving intermediat e formation are developed from microbial reaction fundamentals and thermody namic principles. Biological reactions proceed through intermediates, which sequester carbon and electrons whenever their degradation is relatively sl ow. Modeling intermediate formation and subsequent utilization requires eva luation of the distribution of electrons, energy, and macronutrients (C and N) between energy-generating pathways and cell-synthesis pathways for each step in the mineralization of the primary electron-donor substrate. We des cribe how energy and electron ba lances a re utilized to predict the stoich iometry for each step of a multi-step degradation process. Each stoichiomet ric relationship developed predicts substrate utilization, cell growth, and the formation of other products (e.g., H2CO3 or H+) for one step in the pa thway to full mineralization. A modeling example demonstrates how different kinetics for each step in the degradation of nitrilotriacetic acid (NTA) l eads to observed patterns in experimental results, such as a delay in the r elease of H2CO3 after NTA is removed from solution. (C) 2000 John Wiley & S ons, Inc.