I-Corps: Lignin-derived antimicrobials to control bacterial contamination in fuel ethanol fermentation

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The broader impact/commercial potential of this I-Corps project is the development of a sustainable antibiotic replacement, produced from a known waste stream (lignin), for use during fuel ethanol fermentation. In the fuel ethanol industry, traditional antibiotics, such as virginiamycin or penicillin, are introduced prophylactically into the fermentation process to reduce occurrences of bacterial contamination. However, widespread use of such antibiotics has increased the emergence of antibiotic-resistant microorganisms that pose an ever-growing risk to human health and the environment. Additionally, these antibiotics have been shown to persist in downstream coproducts such as distillers’ grains, which is becoming a major concern for consumers of livestock that are fed the byproduct. Therefore, the production of novel antimicrobial agents with similar selective toxicity, better biodegradability, and effectiveness against antibiotic-resistant bacterial strains would be highly marketable and useful in industrial yeast fermentation environments. If commercialized successfully, the proposed innovation may offer industrial consumers a sustainably derived antibiotic product to combat contamination during fermentation without the pitfalls of traditional antibiotics. In addition, valorization of lignin waste streams for value-added products may allow future lignocellulosic-based biorefineries to be more cost-effective.This I-Corps project is based on the development of an antibiotic replacement produced from lignin waste streams. Lignin is one of the most abundant natural phenolic polymers on earth, plays an important role in plants’ natural defense mechanisms, and is currently considered a major waste product in the paper and pulp industries and lignocellulosic biorefineries. Despite the widely reported antioxidant and antimicrobial properties, lignin-derived antimicrobials have poor selectivity thus limiting their real-world applications. The proposed technology offers a potential solution by converting lignin into a cost-effective and biodegradable antimicrobial product that may selectively inhibit bacterial contaminates and increase ethanol yields during fuel ethanol fermentation. By oxidatively depolymerizing lignin into a liquid product under mild reaction conditions, the resulting product has shown selective antimicrobial properties against lactic acid bacteria, including antibiotic resistant strains, without affecting yeast growth and hydrolase activity. Proof of concept has been demonstrated at the lab scale, but further development of the technology demands a better understanding of the potential customer needs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.