Engineering a Biodetoxification Pathway for Lignocellulosic Feedstock
Engineered microbes can convert sugar into a wide variety of valuable chemicals, including fuels, drugs, and materials. Using such microbes, we are helping to create a Renewable Bioeconomy that would replace existing commodity and speciality chemicals with petroleum-free substitutes, reducing the world's dependence on oil and decreasing global carbon emissions. However, pure sugar is expensive and low-cost feedstocks are needed to manufacture competitive biofuel products.
The United States produces over one billion tons of woody, non-food biomass every year, including everything from leftover, non-edible corn stalks and leaves (called corn stover) to the irregular pieces of wood generated by the lumber industry. This woody biomass contains a mixture of lignin, cellulose, and hemicellulose, called lignocellulose. The conversion of our domestically sourced lignocellulosic feedstock into engine-ready biofuel would enable the United States to replace 30% of its transportation fuel with a petroleum-free alternative.
However, a key challenge to an efficient farm-to-fuel process is the presence of significant amounts of furfural and hydroxy-methyl furfural in pretreated lignocellulose. Furfural is a potent microbial inhibitor that shuts down biofuel production. We are engineering a synthetic version of a metabolic pathway that consumes furfural and hydroxy-methyl furfural (HMF) while simultaneously producing useful cellular building blocks. This biodetoxification pathway allows engineered microbes to consume the furfural and HMF in pretreated lignocellulose while manufacturing high-value biorenewable chemicals.
Using this pathway as a general model, we are also critically testing new ways to systematically design and optimize metabolic pathways to manufacture high-value chemical products.