(275a) High Concentration Glucose Production from CELF Pretreated Corn Stover Using Wild Type Clostridium Thermocellum Supplemented with β-Glucosidase

Glucose production from cellulosic biomass can provide a powerful platform on which to build a sustainable fuels industry. Today expensive cellulases are needed to further breakdown pretreated biomass into sugars with high yields. In response, researchers have turn towards biological saccharification of glucan using C. thermocellum, a highly cellulolytic anaerobe possessing cellulosomes capable of glucan saccharification at high rates and yields. However, C.thermocellum does not produce much β-glucosidase, a necessary enzyme for cellobiose hydrolysis into glucose. Additionally, Co-solvent Enhanced Lignocellulosic Fractionation (CELF) has been shown to be very effective at producing glucan solids from corn stover that are highly susceptible to enzymatic hydrolysis. Thus, the objective of this research is to develop a process by which C. thermocellum supplemented with β-glucosidase can achieve high yields of glucose when fed CELF pretreated corn stover solids at high concentrations (>100g/L). Advantages of the process include: 1) reduction of expensive fungal cellulases, 2) no need for genetic engineering, and 3) high glucose concentrations. CELF pretreatment prepared corn stover for biological conversion, and the resulting washed solids were loaded into 50 mL bottles at a 50-100 g/L glucan loading for incubation with C.thermocellum supplemented with β-glucosidase at 60°C with a shaking speed at 180rpm. Some samples were also supplemented with sodium azide to suppress cell metabolism and enhance glucose yields. Results will be compared for active and inactive C.thermocellum cultures and to results from conventional fungal hydrolysis at high and low loadings at 50°C, pH 5, and 150 rpm.