Magdalena Plotka

Deep eutectic solvents (DESs) have been intensively investigated in recent years for their antibacterial properties, with DESs that comprise organic acids (OA‐DESs) showing promising antibacterial action. However a majority of the reports focused only on a limited number strains and techniques, which is not enough to determine the antibacterial potential of a substance. To bridge this gap, the antibacterial activity of classical DESs and OA‐DESs is assessed on twelve Gram‐negative and Gram‐positive bacteria strains, with some of them exhibiting specific resistance toward antibiotics. The investigated formulations of OA‐DESs comprise glycolic, malic, malonic, and oxalic acids as representatives of this group. Using a range of microbiological assays as well as physicochemical characterization methods, a major difference of the effectiveness between the two groups is demonstrated, with OA‐DESs exhibiting, as expected, greater antibacterial effectiveness than classical DESs. Most interestingly, slight differences in the minimum inhibitory and bactericidal concentration values as well as time‐kill kinetics profiles are observed between Gram‐positive and Gram‐negative strains. Transmission electron microscopy analysis reveals the effect of the treatment of the bacteria with the representatives of both groups of DESs, which allows us to better understand the possible mechanism‐of‐action of these novel materials.

One of the biggest challenges faced by food producers is ensuring microbiological safety. Despite strict criteria for food products, foodborne diseases are a global problem and pose a real risk to consumers. Therefore, it is necessary to identify new and more effective methods for eliminating pathogens from food and the food processing environment. According to the European Food Safety Authority (EFSA), the most common foodborne diseases are caused by Campylobacter , Salmonella , Yersinia , Escherichia coli , and Listeria . Out of the five listed, four are Gram‐negative bacteria. Our review focuses on the use of bacteriophages, which are ubiquitous bacterial viruses, and bacteriophage endolysins to eliminate Gram‐negative pathogens. Endolysins cleave specific bonds within the peptidoglycan (PG) of the bacterial cell, causing the cell to burst. Single phages or phage cocktails, which are, in some instances, commercially available products, eliminate pathogenic bacteria in livestock and various food matrices. Endolysins have matured as the most advanced class of antibacterial agents in the clinical sector, but their use in food protection is highly unexplored. Advanced molecular engineering techniques, different formulations, protein encapsulation, and the addition of outer membrane (OM) permeabilization agents enhance the activity of lysins against Gram‐negative pathogens. This creates space for groundbreaking research on the use of lysins in the food sector.