Ethanol Production by Soy Fiber Treatment and Simultaneous Saccharification and Co-Fermentation in an Integrated Corn-Soy Biorefinery

Abstract

Insoluble fiber (IF) recovered from the enzyme-assisted aqueous extraction process (EAEP) of soybeans is a fraction rich in carbohydrates and proteins. It can be used to enhance ethanol production in an integrated corn-soy biorefinery, which combines EAEP with traditional corn-based ethanol processing. The present study evaluated IF as a substrate for ethanol production. The effects of treatment of IF (soaking in aqueous ammonia (SAA), liquid hot water (LHW), and enzymatic hydrolysis), primarily simultaneous saccharification and co-fermentation (SSCF), as well as scaling up (250 mL to 60 L) on ethanol production from IF alone or a corn and IF slurry were investigated. Enzymatic hydrolysis (pectinase, cellulase, and xylanase, each added at 5% soy solids during simultaneous saccharification and fermentation/SSCF) was the best treatment to maximize ethanol production from IF. Ethanol yield almost doubled when SSCF of IF was performed with Saccharomyces cerevisiae and Escherichia coli KO11. Addition of IF in dry-grind corn fermentation increased the ethanol production rate (~31%), but low ethanol tolerance of E. coli KO11 was a limiting factor for employing SSCF in combination corn and IF fermentation. Nonlinear Monod modeling accurately predicted the effect of ethanol concentration on E. coli KO11 growth kinetics by Hanes-Woolf linearization. Collectively, the results from this study suggest a potential of IF as a substrate, alone or in dry-grind corn fermentation, where it enhances the ethanol production rate. IF can be incorporated in the current bioethanol industry with no added capital investment, except enzymes.

Underutilized Lignocellulosic Waste as Sources of Feedstock for Biofuel Production in Developing Countries

“…It was concluded that SSCF increased ethanol production and can serve as an efficient lignocellulosic waste conversion process to ethanol. Another report (Sekhon et al, 2018) further revealed that the production of ethanol from insoluble fiber doubled when SSCF with S. cerevisiae and E. coli KO11 was used as a conversion process. The three major steps involved in the lignocellulosic biomass conversion (enzymes production, biological hydrolysis of biomass to sugars and oligomers, and fermentative metabolites production) can be combined into a single process known as CBP.…”

Identification and Genetic Dissection of Resistance to Red Crown Rot Disease in a Diverse Soybean Germplasm Population

“…Soybeans [Glycine max (L.) Merrill] are grown worldwide mainly for their high values in oil and protein, yielding over 360 million metric tons in 2020 [1]. The need for soybean production continues increasing as it is essential in feeding humans, animals, and the industries for producing biofuel, ethanol, among others [2][3][4]. Unfortunately, several factors arising from biotic and abiotic stress are implicated in limiting the potential of soybeans to attain high yield and quality.…”

Genome-Wide Association Analysis for Resistance to Coniothyrium glycines Causing Red Leaf Blotch Disease in Soybean

“…Soybean is a cash crop used for animal feed, human consumption, soil fertility improvement, and industrial use for ethanol and biofuel production [ 1 , 2 , 3 ]. Soybean is a legume rich in oil and protein content [ 4 ].…”