Effect of benzoic acid on the ammonium transport system of Zygosaccharomyces bailii

Summary A study of the ammonium transport system of Zygosaccharomyces bailii was carried out using methylammonium as a non-metabolizable analogue. Benzoic acid in the growth medium decreased the capacity of the transport system from 1.46 ± 0.11 mmol.g^–1.h^–1 to 0.41±0.04 mmol.g^–1.h^–1, while the affinity for ammonium was not significatively affected. Although ammonium uptake was inhibited by benzoic acid, the ammonium transport system was still active at preservative concentrations which fully inhibited growth suggesting that inhibition of growth was not governed by the uptake of this nutrient.