Monday, May 4, 2009
9-52

Micellar Enhanced Detoxification and Extractive Fermentation in Surfactant Systems for Biofuel Production

Bin Wang and Hao Feng. Energy Biosciences Institute, University of Illinois at Urbana-Champaign, 382F-AESB, 1304 W Pennsylvania Ave, Urbana, IL 61801

A major obstacle for effective fermentation of monomeric sugars in lignocellulosic hydrolysates is the presence of inhibitory compounds which are toxic to fermenting microorganisms. The toxic compounds can be divided into the following groups: sugar degradation products, lignin degradation products, compounds derived from lignocellulose structures, heavy metal ions, and fermentation end products. In some cases, the end product inhibition is the bottleneck of biofuel production, for example, butanol fermentation. Typically microorganisms can produces less than 20 g/L butanol due to butanol toxicity to the culture. Generally speaking, among all the inhibitory compounds, phenolics are most toxic.

The purpose of this research is to remove inhibitors from hydrolysates or fermentation broth with selected non-toxic surfactant systems. Utilizing the solubilization and uneven partition ability of surfactant micelles (and/or microemulsions), the inhibitory compounds would be extracted into the micelles. The micelles could aggregate and precipitate when the system temperature is above surfactants’ cloud point.


Selected phenolic compounds, such as ferulic acid, vanillin and syringaldehyde were completedly removed by 1% nonionic surfactant block copolymer L62 D in a model system. Around 90% p-coumaric acid and a small amount (10%) furfural were removed as well. At mild pH 5.5, acetic acid and formic acid, etc in disassociated forms can not be removed. An advantage of the surfactant cloud point extraction systems is no sugar loss. The removal of toxic compounds in hydrolysates can be performed in situ. Fermentation tests in a model system containing butanol showed that the surfactant systems led to better cell growth.


See more of Poster Session 2/Reception
See more of The 31st Symposium on Biotechnology for Fuels and Chemicals (May 3-6, 2009)