ACCELERATING THE RATE OF COMETABOLIC DEGRADATIONS REQUIRING AN INTRACELLULAR ELECTRON SOURCE-MODEL AND BIOFILM APPLICATION

This paper applies our recently acquired knowledge of the large and sy stematic changes in internal reducing power to controlled changes in t he cell's primary electron-donor and -acceptor substrates. The systema tic cellular responses of the NADH/NAD ratio is incorporated into kine tic equations for reductive dehalogenation and oxygenation reactions. Results show that the external donor and acceptor concentrations stron gly affect the percentage removal of hazardous compounds. The simplest strategy for maximizing the efficiency of reductive dehalogenation is to maintain a saturating concentration of the primary electron donor, or, as a next best alternative, to minimize the concentration of elec tron accepters. For mono- or dioxygenation reactions, consistently hig h percentage removals can be achieved when the concentrations of both primary substrates are high. Removals of carbon tetrachloride in denit rifying biofilm experiments are in perfect accord with the model predi ctions for reductive dehalogenation. They show a dramatic increase in percentage removal when the primary electron acceptor (NO3) is removed from the reactor and a substantial decrease when the electron donor ( acetate) is removed. Thus, the biofilm experiments verify that biodegr adation reactions can be accelerated dramatically by manipulation of p rimary donor and acceptor concentrations and in a manner consistent wi th modeling predictions based on the internal reducing power.