Exploitative Competition of Microorganisms for Two Complementary Nutrients in Continuous Cultures

Abstract

This paper concerns the exploitative competition of two microorganisms for two complementary nutrients in the continuous culture. Consumption of the limiting resources follows the Holling Type II functional response or, equivalently, Michaelis–Menten kinetics, generalized to the two-resource situation. The predicted biological conditions which should give rise to each of the possible competitive outcomes are presented in detail and analyzed globally. A major conclusion is that each of the four outcomes of classical Lotka–Volterra two-species competition theory has multiple mechanistic origins in terms of consumer-resource interactions. It is also shown that all four classical outcomes, including the case in which winning depends on the initial abundances of the competitors, can arise for this purely exploitative competition. Moreover, the outcomes of this exploitative competition can be predicted, in advance of actual competition, from measurements made on each species grown by itself on the resources.