The influence of high substrate concentrations on microbial kinetics

TLDR

High substrate concentrations inhibit microbial growth and can distort metabolism. The authors derive and test mathematical models of substrate inhibition across the full concentration range, including low‑substrate stimulation, and use one model to formulate equations for batch, continuous, and exponential‑feed reactors. Comparing continuous and exponential‑feed cultures reveals a novel experimental approach to assess how cell age distribution influences culture properties and metabolism.

Abstract

Abstract High substrate concentrations inhibit growth and may distort the metabolism of microorganisms. Mechanisms causing substrate inhibition are discussed and used to derive several mathematical models representative of the entire concentration range, including stimulation of growth by low substrate concentrations. These kinetic models are tested with a variety of batch culture measurements of specific growth rate and respiration rate at widely‐ranging substrate concentrations. Using one of the kinetic models, equations are developed for batch, continuous, and exponential‐feed reactors. Comparison of results obtained in continuous culture with results from exponential‐feed culture systems is shown to offer a novel experimental method for evaluating the effect of the cell age distribution on the properties and metabolic activity of a culture.