PRETREATMENT OF WHEAT-STRAW AND CONVERSION OF XYLOSE AND XYLAN TO ETHANOL BY THERMOPHILIC ANAEROBIC-BACTERIA

Wheat straw was pretreated by wet oxidation (oxygen pressure, alkaline conditions, elevated temperature) or hydrothermal processing (without oxygen) in order to solubilize the hemicellulose, facilitating bio-co nversion. The effect of oxygen pressure and sodium carbonate addition on hemicellulose solubilization was investigated. The two process para meters had little effect on the solubilization of hemicellulose. Howev er alkaline conditions affected the furfural formation whereas oxygen had no effect. After pretreatment, the filtrate was used as a fermenta tion medium for thermophilic anaerobic bacterin. Of five different the rmophilic bacteria used in this study only two strains produced ethano l with xylan as substrate, one of them being the strain A3 isolated fr om an Icelandic hot-spring. Probably other degradation products formed in the presence of oxygen might act as inhibitors. Adaptation of the microorganism to the wet oxidized filtrate was also examined. Copyrigh t (C) 1997 Elsevier Science Ltd.