(396f) Lignin Cationization: Towards Waste Valorization and Combating Antibiotic Resistance

Antibiotic resistance is a severe threat to animal and human health. Many bacterial strains continue to evolve to show resistance against the actions of common antimicrobial agents. This requires the design of new antimicrobial agents that can kill resistant bacteria. On the other side, while the search for more efficient antimicrobials continues, more than $50 billion is spent every year to handle antibiotic resistance in the United States. Thus, if we can design both low-cost and high-efficacy antimicrobials, we will not only be able to deal with antibiotic resistance, but also save human, animal, and aquatic lives. This talk will present our recent effort to design an antimicrobial agent using neglected biomass lignin coming from pulp and paper industries, biorefineries, and agricultural farms. Every year 100,000-200,000 tons of lignin is produced, whereas only 1-2% of this lignin is attempted to valorize. In this work, we rendered cationic functionalities to lignin which can non-specifically bind to negative charges of the outer cell envelope of bacteria, and lead to morphological and compositional alterations of bacteria leading to cell death/growth inhibition. Such non-specific interaction-induced antimicrobial activities stand unique as many notorious pathogens find it difficult to show resistance to such actions. Our results show that treating both wild-type and kanamycin-resistant E. coli with cationic lignin (QAL) can kill ~90% of the bacteria, and lead to ~100% growth inhibition. Combining the findings from scanning electron microscopy, Nile Red staining, and cell permeability tests, we revealed that cationic lignin can alter the lipid bilayer of bacteria and cause leakage of cellular components which appeared to be the root cause of the antimicrobial activity of QAL. Overall, this work demonstrated the high potential of low-cost and bio-renewable lignin in fighting against antimicrobial resistance.