New Approach to Visualize Biomass Solubilization During Ionic Liquid Pretreatment

Auto-fluorescent mapping of plant cell walls was used to visualize cellulose and lignin in pristine switchgrass stems.

The Science

Joint BioEnergy Institute researchers have developed a technique, based on the natural autofluorescence of plant cell walls, that enables the dynamic imaging of biomass solubilization during ionic liquid pretreatment. Using this technique, researchers can accurately and quickly assess the ionic liquid’s performance without the need for labor-intensive and time-consuming chemical and immunological labeling. Working with switchgrass and using the ionic liquid known as 1-n-ethyl-3-methylimidazolium acetate (EmimAc), the researchers observed a rapid swelling of secondary plant cell walls within 10 minutes of exposure at relatively mild pretreatment temperatures (120°C). This reaction indicates a disruption of hydrogen bonding within cellulose and between cellulose and lignin. The swelling was followed by complete dissolution of biomass over 3 hours. By adding water to the solubilized biomass mixture, cellulose can be precipitated out and separated from the lignin, which remains in solution. This recovered cellulose was efficiently hydrolyzed into its sugar components by a commercial cellulase cocktail over a relatively short time interval. Currently, those ionic liquids that are most effective at dissolving plant cell-wall polymers are prohibitively expensive for use on a mass scale. Understanding how ionic liquids are able to dissolve lignocellulosic biomass could pave the way for finding new and better varieties for use in biofuel production.

BER Program Manager

Dawn Adin

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Singh, S., B. A. Simmons, and K. P. Vogel. 2009. “Visualization of Biomass Solubilization and Cellulose Regeneration During Ionic Liquid Pretreatment of Switchgrass,” Biotechnology and Bioengineering 104(1), 68–75. DOI:10.1002/bit.22386.