Cellulosic Biofuels

For the 2007-08 academic year, Dr. Curtis went on sabbatical, in which he (1) consulted as a technical advisor for Green Fuels, one of the first algae biofuels companies, and (2) immersed himself in the techniques of molecular biology. Since then, genetic engineering has become a staple of the CurtisLab 'toolkit'. With CurtisLab's long history of work in plant propagation and early entry into the world of algae biofuels, research in cellulosic biofuels--- or as Curtis explains it CurtisLab's 'sticks-to-fuels' work---was a natural evolution in seeing plants from 'Cradle to Grave'. Dr. Curtis has given invited talks on this theme, encompassing his full spectrum of research, respectively in 2014 at Arkansas' (P3) Center for Plant Powered Production and i n 2015 at Pacific Northwest National Lab (PNNL).

In part as a response to our work in metabolic engineering, in which our metabolic engineering review points out that despite over 30 years of global research and huge investment in the field, native biology is still orders of magnitude more productive than any constructs derived through metabolic engineering (see above). Therefore, our approach to cellulosic fuels took a 'division of labor' or DOL approach, wherein the labor of (1) breaking down biomass and (2) converting biomass into fuel is divided between multiple organisms. Specifically, Clostridium phytofermentans, obligately anaerobic, degrades lignin to make cellulose more accessible while yeast, a facultative anaerobe, converts the biomass into fuel. In the process, we have studied the biofilm behavior of cellulytic C. phytofermentans. Tangential efforts have included variations on this consortia, including one engineered to consume syngas, and a collaboration with PSU Prof. Seong Kim to use SFG (Sum Frequency Generation) spectroscopy to compare 'white-rot' fungi (i.e. Phanerochaete chrysosporium and Ceriporiopsis subvermispora) to accomplish pre-treatment of biomass by consuming lignin to make the cellulose more accessible.

Synergistically taking advantage of other areas of CurtisLab's expertise, CurtisLab partnered with Dr. Andrew Tolonen, with whom Dr. Curtis had shared a lab bench during his sabbatical at Harvard, and Dr. Mohandass Ramya to evolve a more ethanol-tolerant strain of C. phytofermentans as well as metabolically-engineer for increased ethanol production. Similarly, we are also translating this success into introducing metabolic pathways to bypass ethanol fermentation for preference to instead produce hydrocarbons.

In line with CurtisLab's philosophy of sustainability and long history of low-cost, scaleable technology this 'sticks-to-fuel' consortia has the ultimate goal of a simplified process that can be scaled down to an 'on farm' fuel production system to minimize costs associated with biomass transport. Similar to our Hydrostatically-powered Temporary Immersion Bioreactor (Hy-TIB) for plant propagation, We are also interested in utilizing low-cost bioreactor design and operational principles. In particular, we had developed a plastic-lined bioreactor to facilitate a low capital investment process paradigm.