Production of ethanol from wet oxidised wheat straw by Thermoanaerobacter mathranii

The wet oxidation process (water, oxygen, elevated temperature, sodium carbonate) was investigated as a means of solubilising hemicellulose from wheat straw. Sixteen different combinations of oxygen pressure and sodium carbonate concentration were applied. The hemicellulose hydrolysates were evaluated with respect to total sugars, xylose, and 2-furfural produced. The concentration of sugars tended to be highest in hydrolysates produced at high oxygen pressures, whereas the concentration of 2-furfural was lowest in hydrolysates 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 the hydrolysates were fermented by T. mathranii A3M1. However, the solubilised hemicellulose was only partly available for fermentation by the bacteria. Treatment with the commercial enzyme Celluclast® or with acid hydrolysis improved the ethanol yield from the hydrolysates. Treatment with PentopanTH Mono BG or Pulpzyme® HC, both endo-1,4-β-xylanases, had no effect neither had co-cultivation with the xylanase-producing Dictyoglomus B4.

[1]  J. Wiegel,et al.  Production of ethanol from biopolymers by anaerobic, thermophilic, and extreme thermophilic bacteria. III. Thermoanaerobacter ethanolicus JW200 and its mutants in batch cultures and resting cell experiments , 1983 .

[2]  Barbara J. Goodman,et al.  Biotechnology for production of fuels, chemicals, and materials from biomass , 1993 .

[3]  R. Blanchette,et al.  Biodegradation of Hemicelluloses , 1990 .

[4]  Lee Rybeck Lynd,et al.  Fermentation of Cellulosic Substrates in Batch and Continuous Culture by Clostridium thermocellum , 1989, Applied and environmental microbiology.

[5]  Gary D. McGinnis,et al.  Biomass pretreatment with water and high-pressure oxygen. The wet-oxidation process , 1983 .

[6]  G. Sayler,et al.  Bioconversion of D‐Xylose and Pretreated Oak Sawdust to Ethanol Using Clostridium Thermosacchrolyticum by Batch and Continuous Up‐Flow Reactors , 1988 .

[7]  B. Ahring,et al.  Thermoanaerobacter mathranii sp. nov., an ethanol-producing, extremely thermophilic anaerobic bacterium from a hot spring in Iceland , 1997, Archives of Microbiology.

[8]  Ralph P. Overend,et al.  Fractionation of Populus tremuloides at the pilot plant scale: optimization of steam pretreatment conditions using the STAKE II technology , 1991 .

[9]  J. Zeikus,et al.  Ethanol Production by Thermophilic Bacteria: Fermentation of Cellulosic Substrates by Cocultures of Clostridium thermocellum and Clostridium thermohydrosulfuricum , 1981, Applied and environmental microbiology.

[10]  K. Jensen,et al.  Pretreatment of wheat straw and conversion of xylose and xylan to ethanol by thermophilic anaerobic bacteria , 1996 .

[11]  A. Thomsen,et al.  Optimization of wet oxidation pretreatment of wheat straw , 1998 .

[12]  P. Biely.  Microbial xylanolytic systems , 1985 .

[13]  A. Bjerre,et al.  Pretreatment of wheat straw using combined wet oxidation and alkaline hydrolysis resulting in convertible cellulose and hemicellulose , 2000, Biotechnology and bioengineering.

[14]  D. Fengel,et al.  Wood: Chemistry, Ultrastructure, Reactions , 1983 .

[15]  Guido Zacchi,et al.  Cost Analysis of Ethanol Production from Willow Using Recombinant Escherichia coli , 1994, Biotechnology progress.

[16]  A. Bjerre,et al.  Thermal decomposition of dilute aqueous formic acid solutions , 1992 .

[17]  N. Meinander,et al.  Fed-batch xylitol production with two recombinant Saccharomyces cerevisiae strains expressing XYL1 at different levels, using glucose as a cosubstrate: a comparison of production parameters and strain stability. , 1997, Biotechnology and bioengineering.