A limited number of bacteria, yeast and fungi can convert hemicellulose or its monomers (xylose, arabinose, mannose and galactose) into ethanol with a satisfactory yield and productivity. In the present study we tested a number of thermophilic enrichment cultures, and new isolates of thermophilic anaerobic bacterial strains growing optimally at 70–80°C for their ethanol production from d-xylose. The new isolates came from different natural and man-made systems such as hot springs, paper pulp mills and brewery waste water. The test was composed of three different steps; (i) test for conversion of d-xylose into ethanol; (ii) test for viability and ethanol production in pretreated wheat straw hemicellulose hydrolysate; (iii) test for tolerance against high d-xylose concentrations. A total of 86 enrichment cultures and 58 pure cultures were tested and five candidates were selected which successfully fulfilled the criteria defined for the screening test.
Present address: Chr. Hansen A/S, DK-2970 Hørsholm, Denmark.
Thermophiles 2003, a held at University of Exeter, 15–19 September 2003