Comparing the Effects of Interactive and Noninteractive Complementary Nutrients on Growth in a Chemostat

James P. Braselton, Georgia Southern University
Martha L. Abell, Georgia Southern University
Lorraine Braselton, Georgia Southern University


We compare the effects of interactive and noninteractive complementary nutrients on the growth of an organism in the chemostat. We also compare these two situations to the case when the nutrients are substitutable. In previous studies, complementary nutrients have been assumed to be noninteractive. However, more recent research indicates that some complementary nutrient relationships are interactive. We show that interactive complementary and substitutable nutri-ents can lead to higher population densities than do noninteractive complementary nutrients. We numerically illustrate that if the washout rate is high, an organism can persist at higher densities when the complementary nutrients are inter-active than when they are noninteractive, which can result in the extinction of the organism. Finally, we present an ex-ample by making a small adjustment to the model that leads to a single nutrient model with an intermediate metabolite of the original substrate as the nutrient for the organism.