Tomato leaf microstructure affects the adhesion and localization of Salmonella enterica as shown using biomimetics

Non-typhoidal Salmonella enterica serovars are a major cause of diarrheal diseases worldwide and represent a significant health concern. Several Salmonella outbreaks worldwide originated from bacteria residing on plants, specifically on leaves. Understanding the adhesion and survival of Salmonella upon the leaf surface is, hence, of great importance. Among other factors involved in the localization and adhesion of Salmonella to the leaf surface, the surface microstructure did not receive significant attention. Here, we study the localization and adhesion of Salmonella to the surface of tomato leaves, with emphasis on the role of the leaf surface microstructure. To do so, we use biomimetics, a field in chemistry and material sciences aimed at mimicking biological systems. We formed synthetic replication of the leaf surface microstructure, to isolate the microstructure property from all other leaf properties. We found that the distribution of Salmonella upon the leaf surface is not random and there is a clear localization preference to the intercellular spaces and the trichomes. We found that this localization repeats in the synthetic system, suggesting this phenomenon is due to the microstructural features of the leaf. The localization of Salmonella on the trichome is independent of flagella, curli or cellulose, and does not require bacterial viability. However, the overall adhesion of Salmonella to both natural and synthetic leaf surfaces decreased in the cellulose mutant. This result emphasizes the strength of the model synthetic system we developed. A better understanding of Salmonella interaction with leaf surfaces could yield new directions for prevention methods. The findings in this research could assist in the development of such directions.