Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
We explored the use of the white-rot fungus, Trametes versicolor, as an inexpensive biological pretreatment agent for canola straw destined for biofuel production. Specifically, we used a T. versicolor strain deficient in cellulose dehydrogenase (CDH) activity to further investigate the role this enzyme plays in lignocellulose deconstruction. Twelve weeks post inoculation, the wild-type strain led to a significant reduction in available glucose and xylose from the straw as determined by acid hydrolysis, while only xylose was reduced in straw inoculated with the CDH-deficient strain. However, both strains led to a significant increase in lignin extractability after organosolv treatments, suggesting that CDH is involved in cellulose catabolism rather than lignin deconstruction. The soluble fraction of the fungal-treated biomass was enriched with acid lignin moieties and had significantly reduced levels of HMF and furfural. Two-stage saccharification of the organosolv residue from the mutant-treated straw yielded >90% of the theoretical glucose available, while the theoretical yield of the wild-type strain was similar to untreated straw. The mutant strain also decreased the processing energy required to grind the straw while enhancing the pelleting characteristics of the material, thereby greatly improving the overall energy balance of the process. The results of this study not only demonstrate that CDH plays a role in cellulose depolymerization rather than delignification, but also highlight the utility of the CDH-deficient T. versicolor strain as an effective biological pretreatment agent in biomass-to-biofuel applications.