Production of ethanol from wet oxidised wheat straw by Thermoanaerobacter mathranii

The wet oxidation process (water, oxygen, elevated temperature, sodium carb onate) was investigated as a means of solubilising hemicellulose from wheat straw. Sixteen different combinations of oxygen pressure and sodium carbon ate concentration were applied. The hemicellulose hydrolysates were evaluat ed with respect to total sugars, xylose, and 2-furfural produced. The conce ntration of sugars tended to be highest in hydrolysates produced at high ox ygen pressures, whereas the concentration of 2-furfural was lowest in hydro lysates produced at low oxygen pressures and high carbonate concentrations. Fermentation of the hydrolysates was carried out using Thermoanaerobacter mathranii strain A3M1. No significant inhibitory effect was observed when t he hydrolysates were fermented by T. mathranii A3M1. However, the solubilis ed hemicellulose was only partly available for fermentation by the bacteria . Treatment with the commercial enzyme Celluclast(R) or with acid hydrolysi s improved the ethanol yield from the hydrolysates. Treatment with Pentopan (TH) Mono BG or Pulpzyme(R) HC, both endo-1,4-beta-xylanases, had no effect neither had co-cultivation with the xylanase-producing Dictyoglomus B4. (C ) 1998 Published by Elsevier Science Ltd. All rights reserved.