Cybernetic modeling of microbial growth on multiple substrates

TLDR

Microbial growth on multiple substrates is governed by internal regulatory processes that reflect an invariant strategy to optimize cellular goals. The study proposes a goal‑seeking cybernetic model that optimizes cellular response to the environment over a short term. The model uses parameters fitted to single‑substrate growth data and can be applied to batch or continuous cultures of various bacteria on mixed substrates. The model accurately predicts the full spectrum of microbial growth on mixed substrates, including simultaneous and sequential sugar utilization, diauxic lags, and transient responses to varying feed strategies.

Abstract

Abstract The internal regulatory processes, which underlie a variety of behavior in microbial growth on multiple substrates, are viewed as a manifestation of an invariant strategy to optimize some goal of the cells. A goal‐seeking or cybernetic model is proposed here, with the optimization obased on a short‐term perspective of response to the environment. The model parameters are determined from the growth data on single substrates. The model predicts the entire range of microbial growth behavior on multiple substrates from simultaneous utilization of all sugars to sequential utilization with pronounced diauxic lags. It is shown to predict the many variations of the diauxic phenomenon in different growth conditions. The transients in continuous culture growth on mixed substrates caused by varying the feed strategies are easily simulated by this model. The framework of this model can be applied to batch or continuous culture growth of many bacteria on different combinations of substrates.