Concurrent Production and Consumption of Ethanol by Cultures of Pachysolen tannophilus Growing on d-Xylose

Growing cultures of Pachysolen tannophilus concurrently consumed and produced ethanol in the presence of substantial concentrations of d-xylose. Ethanol was also assimilated in the presence of other sugars, the amount depending on the sugar. Less ethanol assimilation occurred with d-glucose than with d-xylose. The rate of ethanol consumption decreased as the concentration of glucose was increased, but some consumption still occurred when 2% glucose was present. The rate increased with the amount of oxygen available to the culture when d-xylose or ethanol was the carbon source. In most instances, estimates of consumption were based on the extent of incorporation of 14C from [1-14C]ethanol into trichloroacetic acid-insoluble material. The results are pertinent to the use of P. tannophilus for the production of ethanol from d-xylose.