Inhibitory effects of acetic acid on respiration and growth of Zygosaccharomyces rouxii

Acetic acid inhibited the formation of cytochromes and the respiratory activity of the halo-tolerant yeast Zygosaccharomyces rouxii R-1. The growth of the yeast was significantly inhibited by 0.5% acetic acid in a medium containing 18% NaCl. This growth inhibition by acetic acid is thought to be related to the halotolelance of the yeast. Proton expulsive activity, which is necessary for the yeast cells to be able to tolerate and grow in a high-saline environment, was markedly lowered in the presence of 0.5% acetic acid, although the plasma membrane ATPase, which drives proton expulsion, seemed not to be inhibited by 0.5% acetic acid. It is assumed that halo-tolerant yeasts are less tolerant to high concentrations of NaCl in the presence of acetic acid because of the reduction of proton expulsive activity, thereby inhibiting growth.