This Small Business Innovation Research Phase I project takes a novel approach to produce improved maize cultivars for bioenergy applications. Lignin in cellulosic biomass creates a barrier that limits conversion of cellulose into biofuels. In the proposed approach, the lignin in crop cultivars is modified to improve conversion to liquid fuels. The Company previously demonstrated the approach in hybrid poplar. The Company has now produced 37 transgenic maize lines with the same lignin modification. The Company is characterizing the biomass composition in the stover (non-seed portions of the maize plant) from these lines, including lignin content, cellulose content, hemi-cellulose content, and protein content. The Company will conduct tests on several plants from each transgenic line for efficiency of conversion of the biomass into ethanol by gentle pretreatment methods. The Company will also conduct field trials with seed collected in the greenhouse from the 37 transgenic maize lines crossed to important maize inbred lines. The field-grown plants will be crossed to generate third-generation seed, and the fodder of the plants analyzed for biomass content and digestibility. The stover of these transgenic maize plants is expected to have increased cellulose extractability and significantly higher rates of conversion to ethanol.
The broader impact/commercial potential of this project will be the development of new, more cost-effective feedstock cultivars of maize for the bio-based products industry. This project will also demonstrate the applicability of this new lignin-modification technology for improving bioenergy feedstocks for both annual and perennial crops. The treatment of cellulosic biomass for sugar extraction for production of biofuels and bioproducts is a challenging and expensive engineering issue. Pretreatment adds as much as 20% to the cost of biofuel production, and can be a limiting factor for economic and environmental viability of the new bioenergy industry. The lignin modification technology developed at Lignolink will be shown to improve the commercial viability of biofuels production by increasing sugar release from biomass, using milder, more- environmentally-friendly pretreatment techniques. The market potential for technology that improves biomass for pretreatment and sugar release is large. The ability to decrease biofuels production costs by improving biomass processing efficiency will help ensure profitability in biofuels production. Corn growers will have a new market for stover, which may surpass the market for first generation biofuels from corn seed. Scientific and technological understanding of a novel means for lignin modification in biomass feedstock plants will also be advanced.
This Phase I/IB research project was aimed at implementing a novel technology for improving biomass characteristics in maize. The technology was previously demonstrated in poplar, but had not been demonstrated in maize, a major agronomic crop in the US that has significant potential for both bioenergy feedstock and livestock forages. Lignin is a primary impediment to extraction of cellulosic energy from crops. This technology takes a novel approach to modifying the lignin structure in plants to increase cellulose extractability and energy conversion efficiencies, while maintaining superior agronomic traits. Our research involved testing several generations of multiple lines of transformed maize to determine the viability of this approach. We have accomplished the objectives in Phase I as proposed and demonstrated the merit and impact of the technology: We have demonstrated successful transformation of maize with our constructs and heritability of the transgene from the T0 (1st) to the T1 (2nd) generation. Results from a field trial confirm that the T1 transformants exhibit normal growth and biomass yields relative to wild type controls. Many of the maize transgenic lines demonstrated an increase in reducing sugars extraction (representative of cellulosic energy) and ruminant digestibility, in both the T0 and T1 generations. Of significance from the plants obtained from the greenhouse, is the finding that certain transformants have close to three times the sugar released in biomass digestions. We have also demonstrated with the T0 and T1 plants that a gentle pretreatment regimen can best reveal differences in digestibility between our transgenic lines compared to wild type plants. This also demonstrates that the Lignolink technology can result in reductions in the extent of pre-treatment needed for sugar release, thus reducing costs in the most expensive step in biofuels production from lignocellulosics. This Phase I/IB project has demonstrated that the Lignolink technology can be an important tool in providing cost effective biomass feedstocks to enable the development of a significant bioenergy system in the US.
