COMETABOLISM OF PHARMACEUTICAL, PERSONAL CARE PRODUCTS BY NITRIFIERS: INTRODUCING A SIMPLE COMETABOLIC FLUX-BASED FRAMEWORK

A simplified cometabolic flux analysis (CoMFA) framework is introduced to explore the effect of the ATP:ADP ratio on the cometabolic potential of nitrifying microbes. A simple system of underdetermined equations and unknowns are used with appropriate objective functions to determine fluxes associated with processing substrate, biomass synthesis, cometabolism, and cell maintenance. The CoMFA model generally predicts that all fluxes increase as the ATP:ADP ratio increases, and the cometabolic flux increases almost 4 fold as the ATP:ADP ratio increases from 1 to 15. The true microbial yield and fe and fs values are all within values predicted by bioenergetic theory. Biomass synthesis is the dominant element of the ATP budget, and cometabolism can account for approx. 5% of the utilization of ATP.