(73g) Moderate Biomass Pretreatment and Its Application In Processing of Plant Biomass Expressing Cell Wall Degrading (CWD) Enzymes

Agrivida Inc has developed a technology that engineers a portfolio of cell wall degrading (CWD) enzymes into biomass plants to address the issue of high cost pretreatment and enzyme production in cellulosic processing. To efficiently evaluate in planta produced CWD enzymes on plant biomass hydrolysis, a moderate pretreatment system was developed to achieve pretreatment effects on the biomass cell wall without deactivating the hydrolytic enzymes within plant. This pretreatment was conducted at a temperature lower than 100 0C and a pH in the range of 4.5-9.0, resulting in no or little toxic products. After pretreatment, the slurry was neutralized and subjected to direct enzymatic hydrolysis without inter-stage washing and separation, in a “consolidated whole slurry” process.  A study for the enzymatic hydrolysis of the pretreated wild-type corn stover demonstrate that 75-88% glucan and over 50% xylan hydrolysis can be achieved for a 3-day enzymatic hydrolysis with Accellerase loadings of 0.1-0.2 ml/g biomass. With this mild pretreatment system, we also conducted a comparative study on processing of wild type and transgenic plant expressing CWD enzymes. The results show that the transgenic plants expressing enzymes can achieve over 50% higher glucan hydrolysis than the control plant with similar or reduced enzyme loading under pretreatment at 65-75 0C, demonstrating the potential of  reducing both pretreatment and enzyme costs in cellulosic bioprocessing by the production of enzymes in plants.