The amount of cellulose converted to glucose increased with the severity of the pretreatment. Saccharification efficiency is also associated with the loss of specific sugars, and subsequent formation of sugar breakdown products.
In a further study funded by the BBSRC / EPSRC Integrated Biorefining Research and Technology Club, the scientists discovered the key factors that determine the efficiency of saccharification. One particular compound, uronic acid, limited the rate at which enzymes worked. The final sugar yield was closely related to the removal of xylan, a common component of plant cell walls. The abundance of lignin, a 'woody' cell wall component, was positively related to the amount of available sugars.
These findings will help improve the efficiency by which straw can be converted to biofuels. For example, adding enzymes that more effectively remove xylan should improve yield. Controlling the level of lignin in the material should also help.
It may even be possible to improve the straw itself, for example to reduce the uronic acid content in the biomass, as suggested by these findings. In the main, oilseed rape has been bred to improve oilseed yield and disease resistance, without paying much attention to the straw. The IFR is working with colleagues at the University of York and the John Innes Centre to see whether there are ways of breeding more "biofuel-ready" varieties of oilseed rape, with the same yields of oilseed but with more amenable straw. In addition, a full understanding of the polysaccharides and other compounds made available during pretreatment may mean other valuable co-products, like platform chemicals, may be viably produced from the surplus straw.
|Contact: Andrew Chapple|
Norwich BioScience Institutes