Lignin, as we learned in class, is a basic structural component of cell walls, and a major contributor to their recalcitrance which serves as a huge barrier to their use in biofuels. The approach taken by these researchers was to modify the lignin pathway in switchgrass through utilization of the comt mutants. This group of mutants affect the transformation of coniferyl alcohols to G lignin and then to S lignin via the caffeic acid 3-O-methyl-transferase gene. It was shown that this trait was continued through the outcross which is important for production of these plants on a larger, industry scale. Additionally, increased levels of other cell wall component sugars were observed in comt 2 and comt 3 mutants which was predictable: this is the plants way of compensating for decreased lignin content. Simultaneous Saccharification and Fermentation (SSF) was used to analyze the amount of ethanol produced. It was found that the higher severity of the pre-treatment, the more ethanol was produced. Additionally, the comt 2 & 3 mutants outproduced WT plants by 80%- an astronomical number. Even with less severe pre-treatments, comt 2 plants were able to out-produce WT plants significantly. This would reduce production costs because lower enzyme doses would suffice- 200-400% less enzymes would be required if pretreatments were used. Bottom line, these researchers have found a way to modify the lignin pathways in plants and developed acid pre-treatment techniques which overall reduce ethanol production costs- hopefully the first step in increasing ethanol production.
Conference Post #3: Lignin Modification in Switchgrass