Conversion of xylose to ethanol by a novel phenol-tolerant strain of Enterobacteriaceae isolated from olive mill wastewater

Abstract

A xylose-fermenting bacterium of the family Enterobacteriaceae was isolated from olive mill wastewater. It converted xylose to ethanol with a yield of 0.19 g ethanol g⁻¹ xylose. Although phenolic compounds normally inhibit pentose-utilizing microorganisms, this isolate was tolerant to phenol. Both the yield and the productivity of xylose fermentation decreased by 30% when phenol was added at a final concentration of 0.8 g phenol l⁻¹. Xylose (23 g l⁻¹) was totally fermented to ethanol (4.3 g l⁻¹) within 48 h in the absence of phenol; however, in the presence of 0.8 g phenol l⁻¹, only 3.3 g ethanol l⁻¹ was obtained from the same starting concentration of xylose after 70 h.