The control of bacterial metabolism will be studied at very low growth rates under conditions in which product formation may be uncoupled from cellular growth. Experiments are designed to provide data for the development of structured metabolic models capable of quantitatively predicting microbial growth based on a cell's genetic organization. Fed-batch or cell-recycle reactor systems will be developed to allow accurate measurements of microbial metabolism at controlled rates of nutrient supply. Measurements of cell viability, macromolecular synthesis, and energy consumption will be performed to determine the extent and stability of metabolic uncoupling. Growth rate control of the expression of regulated enzyme networks (regulons) will be measured using radioisotope labelling, two-dimensional gel electrophoresis and enzymatic gene fusions. Initial studies will look at the particular case of phosphate limitation in two model systems: E. COLI in which the behavior can be analyzed in terms of the genetics of the PHO regulon; and B. SUBTILIS in which the regulation of protein secretion, antibiotic synthesis, and sporulation initiation can be investigated.
