Respiratory Inhibition of Debaryomyces hansenii by Acetic Acid and the Protection by Liver Extrac

Studies on the Antimicrobial Mechanism of Acetic Acid Part II

Abstract

Inhibition of respiration and fermentation of Debaryomyces hansenii, by aceti caid and the protection of liver extract were investigated by Warburg's manometric method. (1) At the lower concentration of 0.5%, acetic acid was assimilated by tested yeast as a respiratory substrate, however, 1% solution was entirely not assimilated. (2) When glucose, pyruvic acid, ethanol or a-ketoglutaric acid were used as a fermentable substrate, O₂ uptake and CO₂ production of tested yeast were inhibited at the higher concentration of 0.5% of acetic acid. However, when pyruvic acid was used as a fermentable substrate, CO₂ production was not inhibited even in 3% of acetic acid solution. (3) When pyruvi cacid, ethanol or a-ketoglutaricacid were used as a respiratory substrate, acetic acid inhibited remarkably O₂ uptakecompared to glucose substrate. From this results, it was estimated that acetic acid inhibited oxidative process following acetyl CoA. (4) In case of glucose used as a respiratory substrate, the addition of acidic fraction of liver extract stimulated O₂ uptake of the yeastcell. From this results, it was suggested that acidic substances in liver extract haveprotective effect for respiratory inhibition by acetic acid.