Gen 1 biofuels derived from corn, sugar cane, and oilseeds have been instrumental in developing an infrastructure for feedstock, manufacturing facilities, markets, and marketing mechanisms for 25 billion gallons/year of renewable transportation fuels, worldwide. Gen 2 biofuels represent the next step in the evolution of sustainable sources of renewable fuels. Gen 2 fuels are based on feedstocks that are derived from sources that do not impact food production or displace land used for other agricultural purposes while, at the same time, offering a reduced carbon footprint. While key cost drivers will be determined by the transportation fuels sectors, value-added bioproducts derived from the huge quantities of inedible sugars generated as a consequence of Gen 2 biofuel production will begin to make an impact as a source of feedstocks for biochemical production.
The evolution of a transportation infrastructure with a low carbon footprint will require commercialization of industrial processes that transform renewable lignocellulosic resources into second generation (Gen 2) liquid fuels and engines and infrastructure specifically designed to maximize their benefits. Ultimately, successful implementation of Gen 2 fuels will be based on policies that integrate technology, economics, infrastructure, and consumer behavior. Gen 2 fuels have the potential to provide low feedstock/sugar costs, which in turn are attractive to the manufacture of bioproducts.
Gene expression profiles of yeast that co-ferments glucose and xylose
The experience of the North and South American biofuel industries and a renewed availability of natural gas will help to bridge the gap between current energy usage and a more sustainable energy future. In the meantime, technology for renewable fuels must be made ready to facilitate build-out of a new industry. This continues to be a key area in the fundamental research being carried out by LORRE and its partners. This website provides background on LORRE's work and a view of a framework within which Gen 2 technology is rapidly developing. This work includes aviation biofuels, development of new knowledge on microbial and protein based bioprocesses for catalyzing transformation of lignocellulosics to value-added bioproducts, the engineering of economic processes that utilize lignocellulosic feedstocks, and thermochemical processes for cellulose conversion. LORRE's work is based on the fundamental characteristics of catalytic processes that transform heterogeneous plant cell wall tissues into homogeneous fermentable substrates or precursors for transportation fuels – both water soluble and gaseous, and thermochemical processes that directly achieve liquid fuels from renewable cellulosic feedstocks.
The research being carried out in biofuels/bioproducts is addressing factors that either inhibit or deactivate the cellulase enzyme complex responsible for hydrolysis of cellulose and formation of glucose. The impact of phenols is significant, since those are released during pretreatments of lignocellulose and severely inhibit some forms of beta-glucosidase which, in turn, causes a backward cascade that stops cellulose hydrolysis (refer to schematic in the figure below). LORRE research is examining the interactions between lignin derived aromatics, cellulase enzymes, and cellulose deconstruction processes.
Schematic representation of a cascade of enzyme inhibition triggered by phenols released during pretreatment of lingo-cellulose (from Max Planck research Library, Edition Open Access (ISBN 978-3-8442-4282), 131-164, 2013)
Another area of importance is the production of cellulases utilizing fungal microorganisms. Identification of new fungal species, capable of producing cellulases, are being studied, and their fermentation, using pretreated lignocellulosic fermentation substrates, is being scaled-up. The goal of this research is to characterize hydrolytic activities, enzyme stabilities, and compatibility with cellulose to ethanol fermentations. Inhibitors derived from lignocellulosic biomass form a common denominator in limiting hydrolysis and fermentation in cellulose conversion. Fundamental studies are also addressing properties of yeast metabolism that are related to robustness and their ability to efficiently utilize sugars in biomass hydrolysates. This work is multidisciplinary and is carried out at the intersection of microbiology, enzymology, molecular biology, and bioprocess engineering. The goal is to reduce cost of production of Gen 2 biofuels from corn co-products, lignocellulosic feedstocks, or purposely grown energy crops and woody biomass.