Breaking Through Microbial Defences - Organic Acid-Based Deep Eutectic Solvents as a Neoteric Strategy in Bacterial Biofilm, Persister, and Fungal Control

Abstract

This study explores the adaptation of organic acid-based deep eutectic solvents (OA-DESs) as effective antimicrobial agents. Having already demonstrated their efficacy against planktonic bacteria in our previous research, we now investigate their impact on more complex microbial forms, including biofilms, persister cells, and fungi (both human pathogenic and phytopathogenic). Our experiments revealed that OA-DESs effectively eradicated MRSA and Escherichia coli biofilms, inducing significant morphological changes. Notably, a three-log-unit reduction was observed for most OA-DESs at concentrations below 1% v/v, a remarkable achievement for this class of materials. Additionally, with only one exception, OA-DESs did not promote persister cell formation, underscoring their potential for complete biofilm eradication. In another part of our study, OA-DESs were compared to conventional DESs against Candida albicans, Candida auris, and Aspergillus fumigatus. Results showed that while individual DES components exhibited minimal activity, their combination effectively inhibited fungal growth and induced substantial morphological changes. Lastly, OA-DESs were tested against the phytopathogens Zymoseptoria tritici and Venturia inaequalis. Though their activity was less pronounced compared to pathogenic strains, most OA-DESs inhibited the growth of both fungi at the highest tested concentrations. Despite the broad scope of this study, we believe this study provides valuable insights into the potential of DESs as antimicrobial agents, offering a strong foundation for future research and innovation in this field.