Sunday, May 3, 2009
3-108
Effect of Ensiling Transgenic Tobacco Expressing an Endoglucanase Gene on Industrial Processing Efficiency
Deisy Y. Corredor, Kirk L. Pappan, Michael J. Blaylock, and Bryan C. Gerdes. Edenspace Corporation, 1500 Hayes Drive, Manhattan, KS 66502
Bioconversion of lignocellulosic biomass from its unprocessed form as a plant in the field to final commercial products requires four vital processing phases: harvest, storage, pretreatment, and hydrolysis to fermentable sugars. With the development of crop feedstocks tailored for use as cellulosic feedstocks (i.e., plants containing embedded enzymes), the opportunity exists to integrate harvesting and storage phases with pretreatment and hydrolysis. One effective method of long-term biomass preservation and storage is ensilement. The object of ensilement is to preserve the harvested biomass by anaerobic fermentation without losing feed quality. In addition, it would be advantageous if during the preservation period the biomass could be conditioned to aid the downstream bioconversion. Recent data suggests that expression of endoplant enzymes (endo-glucanases) and early activation of those enzymes during storage can complement and subsequently reduce pretreatment requirements, creating favorable conditions to reduce total production costs.
In this study, wild type and transgenic tobacco (containing endoplant enzymes) were ensiled varying time and temperature. Changes in chemical composition and effects on further enzymatic and acid hydrolysis with commercial enzymes due to ensiled storage were then quantified. Compared to wild-type tobacco, transgenic lines displayed greater sugar yields when biomass was digested with commercial enzymes. These properties were further enhanced by ensilement at room temperature for 10 days. These results demonstrate that ensilement has the potential to reduce pretreatment requirements and lower the cost of existing bio-processing regimes. This project was supported in part, by the U.S. Department of Energy, Contract DE-FG02-07ER84770.