Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)
Mercy Ampaw-Asiedu - Prairie View A&M University
Co-Author(s): Jaron Mackey and Michael Gyamerah, NSF CREST Center for Energy and Environmental Sustainability and Department of Chemical Engineering Sela Woldesenbet, Coorperative Agricultural Research Center, Prairie View A&M University, Prairie View, TX
Carbon-neutral biofuels from cheap and readily available lignocellulosic biomass are being considered as alternatives to non-renewable fossil fuels for transportation fuels. However, biomass feedstocks are currently uneconomic to hydrolyze into fermentable sugars. Ionic liquids have been proposed to overcome this draw back due to their efficiency to hydrolyze biomass under mild conditions to fermentable sugars. A genetically engineered strain Zymomonas mobilis AX 101 that co-ferments biomass hydrolysates containing glucose, xylose and arabinose was used in this study to take advantage of the exceptional ability of the bacterium Z. mobilis to rapidly and efficiently ferment glucose to ethanol. The research objective is to optimize bioethanol production by fermentation of 1-(1-propylsulfonic)-3-methylimidazilium chloride hydrolyzed lignocellulosic biomass using the Z. mobilis AX101. Authentic glucose, xylose and arabinose were used to simulate lignocellulosic hydrolysates for growth and ethanol fermentation. Growth of Z. mobilis AX 101 was determined by measuring the OD at 600 nm and reading off the cell dry weight using an established calibration curve. The effect of ionic liquid concentration on the kinetics of growth and co-fermentation of the simulated hydrolysate was investigated using 8 mM, 16 mM and 32 mM ionic liquid concentrations. At ionic liquid concentration of 8 mM, the growth decreased by 10% compared to the control, while the decrease was 27 and 67% respectively at 16 and 32 mM concentrations. The ethanol yields on a weight basis were 83.3, 82.2, 67.2 and 30.9% for the control, 8 mM, 16 mM and 32 mM concentrations respectively. The results also show that the recommended ionic liquid concentration of 32 mM for hydrolyzing cellulosic biomass strongly inhibits both growth and ethanol fermentation and reduces ethanol yields. At ionic liquid concentration of 8 mM the hydrolysate could be fermented without additional processing to reduce the concentration to non-inhibitory levels.
Funder Acknowledgement(s): This work is supported by the National Science Foundation (NSF) through the Center for Energy and Environmental Sustainability (CEES) a NSF CREST Center, Award #1036593.
Faculty Advisor: Michael Gyamerah, firstname.lastname@example.org
Role: All part of the research was conducted by me.