Micromixing in fermentors: Metabolic changes inSaccharomyces cerevisiae and their relationship to fluid turbulence

Abstract

Even when microorganisms are grown in highly agitated fermentors, calculation predicts a mismatch between the microscale of the turbulence (where the smallest eddy is typically 50–300 μm diameter) and the cellular dimensions (1–5 μm). The cell thus spends substantial portions of time in an apparently stagnant eddy, depleted of nutrients. The local fluid microscales were measured in a laboratory fermenter to confirm this. Using S. cerevisiae in continuous culture, it is shown that the local microscales influence cell metabolism dramatically. The issues addressed in this study are thus micromixing and microsegregation of reactants and how they influence cell yield.