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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Bioenergy Research » Research » Publications at this Location » Publication #415770

Research Project: New Bioproducts for Advanced Biorefineries

Location: Bioenergy Research

Title: Resourceful and economical designing of fermentation medium for lab and commercial strains of yeast from alternative feedstock-transgenic oilcane

Author
item MAITRA, SHRADDHA - University Of Illinois
item Dien, Bruce
item EILTS, KRISTEN - University Of Illinois
item KUANYSHEV, NURZHAN - University Of Illinois
item JIN, YOUNG-SU - University Of Illinois
item CORTES-PENA, YOEL - University Of Illinois
item GUEST, JEREMY - University Of Illinois
item SINGH, VIJAY - University Of Illinois

Submitted to: Biomass and Bioenergy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Each year the US burns 1.75 billion gallons of aviation fuel (2022), which releases 3% of our greenhouse gas emissions. The U.S. government and U.S. airline carriers are actively promoting sustainable aviation fuel (SAF) as a path to lessen the impact of flying on climate change. ARS researchers (Peoria, Illinois) are working with University of Illinois scientists as well as others to help achieve this goal. The strategy is to develop a new crop based on sugarcane that produces vegetable oil, sugar juice, and fiber. Vegetable oil is readily converted to SAF using well established technology. The fiber can be converted to sugars using "cellulosic" technology. Both the sugars from the juice and fiber can be fermented to ethyl alcohol, which can be converted to SAF using commercial technology. In this study, we found that simply by blending the juice and cellulosic sugars, both sugars can be fermented at the same time using yeast. In fact, the yeast ferment better on the mixture than just cellulosic sugars. The juice also contains nutrients that yeast need to grow and this means there is no need to purchase supplemental ingredients needed by growing yeast. Finally, this means that both sources of sugars can be fermented in the same tank, which saves on equipment costs. This study will be of interest to the aviation and biofuel industries and farmers in the South with an interest in learning about future crop development.

Technical Abstract: Limited tolerance of industrially recognized yeasts towards inhibitors generated during the processing of lignocellulosic biomass to produce fermentable sugars is a major challenge in developing scalable processes for 2nd generation drop-in fuel production. Strategies used to alleviate the inhibitory effects include either detoxification steps and/or the addition of nutrients to the fermentation medium. Although these approaches improve fermentation performance, they increase production costs. Here we have used alternative feedstock -oilcane- cultivars of sugarcane that have been genetically engineered to hyperaccumulate vegetive lipids, for development of fermentation media and evaluated the growth and fermentation of engineered S. cerevisiae strains on it. The oilcane juice contained 204 g/l of soluble sugars as well as amino acids, lipids and phenolics. The bagasse was pretreated at an industrial continuous steam explosion reactor followed by disc milling and enzymatic hydrolysis. The resulting hydrolysate contained 122 g/l of cellulosic sugars as well as acetic acid, furans, lipids, and phenolics. The study demonstrates that adding oilcane juice to the hydrolysate provides the complete nutrients required for propagation of fermenting microorganisms while diluting the concentrations of inhibitors. Two laboratory and one commercial Saccharomyces cerevisiae yeast strains engineered for xylose fermentation were used in this study; two were laboratory strains and third a commercial strain. They were cultured on the juice, hydrolysate, and blends of the two without supplemental nutrients or removal of inhibitors. An equal ratio of hydrolysate and juice was found optimum for growth and fermentation by the S. cerevisiae strains. The cultures benefited from prior adaptation of the seed cultures on blended medium. The best fermentation results were observed for the industrial strain under low aeration conditions: the ethanol yield, specific and volumetric productivities were 0.51 ± 0.001 g/g, 0.27 ± 0.02 g/g.h and 1.95 ± 0.01 g/g.l, respectively.