The single-batch bioconversion of wheat straw to ethanol employing the fungus Trichoderma viride and the yeast Pachysolen tannophylus.

We have developed and optimized a single-batch process of the production of ethanol from wheat straw employing the fungus Trichoderma viride and the yeast Pachysolen tannophylus. T. viride and Aspergillus niger were examined for their ability to produce fermentable sugars from cellulosic waste materials, e.g. different kinds of straw and wood waste. T. viride most efficiently saccharified delignified wheat straw within 3 days at 25-30 degrees C with a yield of reducing sugars of 27 g from 50 g delignified wheat straw. The resulting wheat straw hydrolysates contained xylose and glucose in a 1:1.6 molar ratio. After heat inactivation of fungal activities the sugars were converted to ethanol by the oxygen-tolerant yeast P. tannophylus in the same batch. Under the optimized conditions developed (all weights are per liter) 70 g natural untreated wheat straw (100%) yielded 50 g delignified straw (71.4%), which was saccharified to 27 g reducing sugars (38.6%). Fermentation of the sugars yielded 11.8 g ethanol (16.9%) and followed the molar equation: 1 xylose + 1.6 glucose --> 5.3 ethanol + 5.6 CO2.