Andrew R. Russell

Antibiotic resistance continues to challenge the medical field worldwide, and the need for alternative methods to combat antibiotic resistance is imperative. Plant lectins have shown promising results as a natural anti-biofilm agent by disrupting the biofilm’s ability to adhere by binding to specific monosaccharides in the extracellular polymeric substance (EPS). This study aimed to use the plant lectins, Con A and WGA, to agglutinate to the EPS and inhibit biofilm formation in antibiotic-resistant pathogens like Pseudomonas aeruginosa, Staphylococcus epidermidis, and Stenotrophomonas maltophilia. Initially, minimum inhibitory concentration (MIC) assays were performed, and the final concentration determined was based on a study investigating the impact of plant lectins on biofilm formation for Streptococcus mutans (0.4 mg/mL). 96-well biofilm assays were statistically significant for P. aeruginosa with Con A treatment and S. mutans with WGA treatment. These results indicate that P. aeruginosa treated with Con A reduces the biofilm’s ability to adhere, because of the high volume of mannose-specific monosaccharides in its EPS. Additionally, results for S. mutans indicate that WGA can inhibit the biofilm’s adhesion, because of the presence of N-acetylglucosamine monosaccharides in the EPS. Future research is needed to confirm if plant lectins are a natural anti-biofilm agent.

Microbial biofilms are an increasing threat to human health as they provide protection from both antibiotics and the immune system; therefore, some labs are turning their attention to discovering compounds that can disrupt their formation or break apart established biofilms. Zingerone, a compound found in ginger, has been shown to disrupt biofouling in several Gram-positive and Gram-negative species. To determine if zingerone may be a candidate for general usage, the way in which it disrupts biofouling should be elucidated. Recent results suggest that one of the ways zingerone impacts biofilm formation is by disrupting quorum sensing. Yet many quorum sensing systems exist and it is still unclear which of these are affected by zingerone. This study aims to determine if zingerone disrupts the biofouling of bacteria that use AHL, DSF, and Agr quorum sensing signaling systems. Minimum inhibitory concentration assays were used to determine the maximum concentration of zingerone that the bacteria tolerate, and then biofilm assays were used to determine whether zingerone affected biofilm formation. While this study did not see a statistically significant decrease in biofilm formation in the presence of zingerone, visible differences between the control and treatment wells of Agrobacterium tumefaciens in the qualitative results suggest that technical error may have diminished any statistical significance in the quantitative data.