Unlike the simple starch-based sugars in corn and other grains, the complex polysaccharides that comprise the plant cell walls of non-food lignocellulosic biomass are locked within a tough material called lignin that is very recalcitrant and hard to break down. Researchers in JBEI’s Deconstruction Division are developing new and improved ways to release these polysaccharides and reduce them to fermentable sugars that can be synthesized into biofuels and renewable chemicals – a process called “deconstruction”. The deconstruction process normally requires two steps: (1) pretreatment, typically a thermochemical process that perturbs the structure and chemistry of the plant cell walls to increase the accessibility of the polysaccharides to hydrolytic enzymes, followed by (2) enzymatic depolymerization of the polysaccharides and lignin generated after pretreatment into monomers suitable for bioconversion into biofuels and renewable chemicals.
In terms of the pretreatment process, our focus is on the development of ionic liquids, molten salts that are liquid at room temperature, as a novel means of pretreating lignocellulosic biomass and producing our targeted intermediates: sugars and lignin-derived compounds. We are establishing new approaches into how these ionic liquids can be used as part of a novel process that consolidates pretreatment, depolymerization, and fermentation into a single unit operation that significantly reduces costs and energy requirements. This requires the synthesis and screening of ionic liquids that are compatible with the enzymes and microbes used to complete the biomass conversion process.
In terms of enzymatic depolymerization, we are exploring known ecosystems, such as rain forest floors and composts, for the identification, characterization, and optimization of new microbial and fungal enzymes that are capable of efficiently depolymerizing both the polysaccharide and lignin components of plant cell walls after pretreatment. We are also engineering fungal hosts for the production of recombinant enzymes at high titers.
The Deconstruction Division works closely with the other JBEI Divisions in order to provide the fundamental breakthroughs needed to establish a complete integrated solution for the production of targeted intermediates and products from sustainable lignocellulosic feedstocks.
- Developing the scientific and engineering basis for a scalable and affordable ionic liquid pretreatment technology
- Understanding how microbial communities metabolize lignocellulose before and after pretreatment and identify the genes, pumps and proteins responsible for this activity
- Developing and optimizing a lignocelluloytic enzyme mixture capable of liberating fermentable sugars and lignin monomers at industrially relevant process conditions
- Developing fungal recombinant expression systems capable of producing enzymes at high titers
- Technoeconomic and lifecycle analysis of advanced JBEI technologies to understand their impact in terms of cost and greenhouse gas emissions relative to petroleum