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

Zayed, G., Meyer, O.
Applied microbiology and biotechnology 1996 v.45 no.4 pp. 551-555
Aspergillus niger, Pachysolen, Trichoderma viride, biotransformation, carbon dioxide, equations, ethanol, ethanol production, fermentation, glucose, heat inactivation, hydrolysates, reducing sugars, wheat straw, wood residues, xylose, yeasts
We have developed and optimized a single-batch process for 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) 70g natural untreated wheat straw (100%) yielded 50g delignified straw (71.4%), which was saccharified to 27 g reducing sugars (38.6%). Fermentation of the sugars yielded 11.8g ethanol (16.9%) and followed the molar equation: 1 xylose + 1.6 glucose leads 5.3 ethanol + 5.6 CO2.