Graduate Studies
First Advisor
Paul Blum
Date of this Version
Spring 5-2023
Abstract
In the U.S., an estimated 95% of hydrogen (H2) production is considered grey, which refers to increased rates of emissions and pollutants. To avoid increasing rates of emission, the demand for biohydrogen production has risen drastically over the past 10 years. Biohydrogen, also known as green H2, is considered clean energy that can be used to generate electricity as a renewable fuel source. The use of bioprocessed agricultural biomass is a cost-efficient way to generate biohydrogen. Bioprocessed agricultural biomass such as corn fiber, soybeans, and pistachio shells, liberate fermentable sugars upon undergoing enzymatic hydrolysis and are extracted with the help of a refined cocktail of enzymes called Extremase, which can extract sugars at extremely high temperatures and low pH conditions. The results presented here showed that Extremase has an impact in yielding reducing ends from different agricultural biomass. Extremase has also been shown to be effective in extracting oil and in turn, upon esterification of the lipids, fatty acid methyl esters (FAMEs) from soybeans are produced, resulting in 2-fold higher yield of all lipids with Extremase and no change in the lipid profile. The fermentable sugars obtained from the bioprocessed agricultural biomass were then used as the source of carbon for the growth of hyperthermophilic anaerobic bacterium known as Thermotoga maritima. T. maritima is known to catabolize a wide range of hexoses, such as maltose, and glucose, to efficiently synthesize molecular H2 along with carbon dioxide, acetate, and traces of lactate and theoretically yield 4 moles of H2 per mole of hexose. Gas chromatography was used to identify the molar yield and volumetric productivity of H2 obtained from high cell density T. maritima cultures grown in optimized rich medium, along with that obtained using the various bioprocessed biomass. Out of the different types of biomass tested, reducing sugars from Corn Fiber were the most supporting of T. maritima growth and H2 production. Using Extremase for bioprocessing agricultural biomass and in turn allowing T. maritima, a natural producer of H2, to ferment the extracted sugar for H2 production, is sustainable.
Advisor: Paul H. Blum
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Biological Sciences, Under the Supervision of Professor Paul H. Blum. Lincoln, Nebraska: May, 2023
Copyright © 2023 Aditi Arun