Co-fermentation processes that can consume both sugars and CO2 are emerging as a promising technology to enhance product yield and reduce emissions in biofuels production. A team of scientists at Oklahoma State University (Stillwater, Okla.; www.okstate.edu) are working to accelerate the large-scale adoption of co-fermentation processes and validate the use of industrially significant feedstocks. “Our co-fermentation method leverages advanced microbial engineering techniques, such as CRISPR-based gene editing, to create microbial strains that can tolerate inhibitory compounds present in biomass. By utilizing both sugars and CO2, the co-fermentation process addresses key challenges in traditional fermentation processes, making it more efficient and sustainable for large-scale biofuel production,” explains Hasan Atiyeh, Oklahoma State professor of biosystems and agricultural engineering.
To date, the team has demonstrated co-fermentation processes at liter-scale volumes. Since receiving a patent for a co-fermentation process in 2021, the team has integrated an in-situ separation process to recover butanol during the co-fermentation process and has also tested the ability of three new acetogens to convert CO2 into C2 to C6 alcohols and fatty acids. “We have successfully conducted multiple trials to validate the process, achieving significant advancements in microbial-strain optimization, enzyme activity and product yields,” says Atiyeh. The next steps will involve moving to the pilot scale and exploring partnerships with industry stakeholders to facilitate further scaleup.
One of the most significant breakthroughs in this work has been the validation of corn-steep liquor, a byproduct of corn milling, as a co-fermentation feedstock. “Corn-steep liquor is a cost-effective and renewable resource that provides essential nutrients that enhance microbial growth and biofuel production efficiency. Other promising feedstocks for co-fermentation in the industry include lignocellulosic biomass, such as switchgrass, agricultural residues and other organic waste materials. These feedstocks are abundant and can be sustainably sourced,” adds Atiyeh.
There are currently no co-fermentation processes for sugar and gas running at an industrial scale specifically for biofuels production, but Atiyeh and his team hope to bridge the gap between research and industry with their work.