Producing biofuels from lignocellulosic biomass is being investigated as a possible energy source to reduce the United States’ dependence on foreign oil. One challenge researchers face is that plant cell walls are complex structures composed of cellulose, hemicellulose, lignin, pectin, and protein. Current methods of breaking down these plant cell walls are not cheap, making ethanol production expensive and not a realistic competitor to petroleum.
The major component of hemicellulose is xylan, a five carbon sugar. Enzymes or bacteria could be used to break up the xylan in plant material, making cellulose more accessible to cellulases. The xylan can also be used to produce xylose, from which ethanol can be produced. In sequencing five xylan degrading microbes, researchers hope to identify protein sequences of enzymes which may be helpful in breaking down lignocellulose. Each microbe was sampled from a different location. For example, Amphibacillus xylanus is an anaerobic bacterium, while Mucilaginibacter species were isolated from acidic sphagnum peat bog. Xylanibacter oryzae is a novel bacterium isolated from rice-plant residue in flooded rice-field soil in Japan. Thermobacillus composti is a moderately thermophilic bacterium isolated from a composting reactor. Finally, Cohnella panacarvi is a bacterium isolated from ginseng cultivating soil.
Photo: Gay Austin, US Forest Service
Principal Investigators: Iain Anderson, DOE Joint Genome Institute
Program: CSP 2010