Research Highlights

The biofuels industry has devoted significant efforts to converting lignocellulosic substrates into sugars that can be fermented into biofuels or other bioproducts. However, one of the major bottlenecks for cost-effective conversion in biorefineries has been the fermentation inhibition of yeast or bacteria by pretreatment degradation products.

Up to 20% of the cell wall in grasses is composed of mixed-linked glucan (MLG). The MLG carbohydrate is an important plant-based energy source for human consumption and potentially a readily accessible carbon source for biofuel production.

In September, GLBRC Education and Outreach leaders John Greenler and Leith Nye, in collaboration with Travis Tangen at the Wisconsin Alumni Research Foundation, published a laboratory protocol that facilitates student engagement in bioenergy research.

Most biological catalysts used for biofuel production have come from nature, where there is selective pressure to adapt to changes in the environment. As such, natural populations contain a diversity of genetic traits, some of which may be useful for bioenergy production.

The choice of solvent for lignocellulosic biomass conversion can influence the reaction rate, yield of product, and the type and yield of undesirable side products. Gamma-valerolactone (GVL) is an organic solvent shown to produce a high yield of sugar and solubilized lignin streams from acid-catalyzed biomass.

In order to successfully develop a second-generation biofuels industry, the agricultural sector will need to supply bioenergy feedstocks, which refer to cellulosic biomass (non-food plants), which typically consists of crop residues, perennial grasses, and short-rotation trees.

Plants cell walls contain polysaccharides that can be hydrolyzed into fermentable sugars. Lignin, which is also present in the cell walls, hinders enzymatic saccharification. Thus, lignin must be removed or cleaved prior to saccharification, which requires chemicals and energy and increases cellulosic biofuel production costs.

Lignocellulosic crop residues are a promising alternative feedstock for producing liquid fuels and chemicals for modern biobased economies, and biochemical conversion of lignocellulosic biomass to liquid fuels requires pretreatment and enzymatic hydrolysis of the biomass to yield fermentable sugars. To compete with traditional refineries, biorefineries must achieve high carbohydrate-to-fuel yields with low enzymatic input and facilitate lignin valorization to co-products extending beyond simply using lignin to generate heat and power. Most pretreatment processes require high enzymatic loadings to achieve higher sugar yields under industrially-relevant conditions.