Tuesday, April 30, 2013
Exhibit Hall
It is becoming increasingly apparent that, similar to oil refineries, additional value-added co-products must be produced as part of a biomass-to-fuels process. This can partially be addressed through the effective separation/recovery/use of most of the lignin, hemicellulose, and cellulose after biomass pretreatment. Ideally, a pretreatment process would yield three clean fractions containing cellulose, hemicellulose and lignin. However, the cellulose, hemicellulose and lignin components that comprise the majority of lignocellulosic matrials have been shown to vary with regard to their recalcitrance in terms of their ease of fractionation and recovery using chemical, physical or enzymatic means. For example, hemicellulose, which can act as a hydrophilic “filler” material in the cell wall, is an amorphous low molecular weight polymer which is readily hydrolysed when compared to cellulose and lignin. In addition, there are significant differences in the structure and recalcitrance between agricultural, hardwood and softwood biomass. For example, softwoods contain highly refractory cross-linked guaiacyl rich lignin compared to the syringyl rich lignin in hardwoods. These differences in recalcitrance between biomass components and types can confound fractionation strategies. A pretreatment type or condition that can maximize the ease of hydrolysis of cellulose in many cases sacrifices hemicellulose recovery or does not recover lignin with potential for downstream applications. We have found that a multi-stage pretreatment provided good recover y of the hemicellulose and lignin fractions while enhancing the enzymatic hydrolysis of the cellulose component resulting in 80% conversion with enzyme loadings as low as approximately 7 mg protein (3FPU/g glucan).