Effect of bacterial density and substrate concentration on yield coefficients.

Measurements were made of the yield coefficient during the aerobic metabolism of glucose by a heterogeneous bacterial mixture. Expressed in terms of carbon, the coefficient was approximately 0.48. The value did not vary with initial bacterial densities ranging from 0.4 pg to 40 micrograms of cell carbon per ml and with glucose concentrations ranging from 43 pg to 100 micrograms of carbon per ml. Under all these circumstances, about 44% of the glucose carbon was converted to CO2, and 7.4% was excreted as organic products. The significance of uncharacterized organic substrates contaminating the medium to the coefficients calculated for low glucose concentrations is discussed.