Comparison of alternatives for fermentation for ethanol production from lignocellulose

Purpose and goal

The goal of the project was to compare alternative processes for the production of ethanol from lignocellulose: the more established and researched process where yeast is used and the use of a thermophilic bacterium in order to identify the need for continued development and thus help to catalyze the steps from research to commercialization. The bacteria were studied both in the lab and in the demo scale, and the conclusion is that more research needs to be generated about the bacterium if its benefits will be able to compensate for its disadvantages.

Results and expected effects

Advantages of thermophilic bacteria is that they can consume both hexoses and pentoses as demonstrated in the project. Another advantage is that it has polysaccharide-degrading enzymes and genes for these identified, however no significant activity was measured. Thermophilic bacteria can withstand high temperature which is an additional advantage, however, as showed the bacteria are more sensitive than yeast to inhibitors, oxygen and harvesting conditions and more research needs to be generated if the bacteria´s benefits will outweigh its sensitivity.

Approach and implementation

The project consisted of a labstudie carried out at Lund University in cooperation with Enza Biotech and a demonstration study at the Biorefinery Demo Plant in Örnsköldsvik. The bacterial strain chosen was Geobacillus thermoglucosidasius DSM 2542. It was characterized both in laboratory and demo scale in terms of media needs, consumption of sugars, fermentation products, enzyme activity for the degradation of the polysaccharide, inhibitor sensitivity, oxygen sensitivity and sensitivity to handling, inoculation and up-scaling.