Recycling and complementary food sources hinder oscillatory dynamics in a microbial population

Microbes constantly interact with their environment by depleting and transforming food sources. Theoretical studies have mainly focused on Lotka-Volterra models, which do not account for food source dynamics. In contrast, consumer-resource models, which consider food source dynamics, are less explored. In particular, it is still unclear what physical mechanisms control oscillatory dynamics at a single population level, a phenomenon which can only be captured by a consumer-resource model. Here, we present a minimalistic consumer-resource model of a single microbial population with growth and death dynamics, consuming a continuously replenishing substrate. Our model reveals that decaying oscillations can occur if and only if the timescale of microbial adaptation to food supply changes exceeds the death timescale. This general rule allows us to easily examine additional physical phenomena. We find that microbial necromass recycling or complementary use of multiple food sources reduces the parameter range for oscillations and increases the decay rate of oscillations, stabilizing the dynamical system. Conversely, requiring multiple simultaneous food sources destabilizes the system. Essentially, facilitating growth reduces the likelihood of oscillations. We hope our work will motivate further investigations of consumer-resource models to improve descriptions of environments where food source distributions vary in space and time.