Effect of limonene on ethanol production by Zymomonas mobilis

The effect of orange peel oil on ethanol production by the ethanolgenic bacterium Zymomonas mobilis was investigated. Orange stripper oil produced from orange peel was added in various amounts to determine its effects on ethanol production. Fermentation of model sugar solutions were conducted at 30 and 37 °C. The minimum peel oil concentration that inhibited ethanol production was determined after 24, 48 and 72 h and the two yeasts were compared to one another in terms of ethanol yield. Minimum inhibitory peel oil concentrations for ethanol production at 30 °C were 0.05% after 24 h, 0.10% after 48 h, 0.15% after 72 h, and 0.20% after 96 h. Minimum inhibitory peel oil concentrations for ethanol production at 37 °C were 0.05% after 24 h, 0.10% after 48 h, and 0.20% after 72 h. Peel oil did not inhibit ethanol production after 96 h at a temperature of 37°C.