Attachment of Escherichia coli on plant surface structures built by microfabrication

Consumption of fresh fruits and vegetables contaminated with human pathogenic bacteria has caused numerous outbreaks of food-borne disease in recent years. Understanding the nature of bacterial colonisation on plant surfaces could lead to more effective practices to prevent contamination. The goal of our study was to determine the effect on bacterial attachment of structures mimicking those that occur on plants. Plant surfaces have microstructures in a wide range of sizes and shapes, causing difficulty in separating and understanding individual effects. Microfabrication methods were used to build surface structures on silicon to mimic stomata, trichomes, and grooves between plant epidermal cells. These structures were subjected to a 48-h culture of Escherichia coli tagged with green fluorescent protein. Bacterial attachment characteristics were determined by observation under a confocal laser scanning microscope. The number of bacteria in an area with an array of trichomes was about half of that for the stomata or grooves. Within an array of trichomes, the bacteria level around the base of the trichomes was 4.7 times higher than areas further away. Within an array of stomata, the level of bacteria attaching to the area 2.5–5.0 μm away from the stomatal opening was 35–59 percent higher than the area next to the opening or areas further away. Within an array of grooves, there were no significant location effects. Microstructure geometry and position clearly affected bacterial attachment in our model system.

Research highlights
► Escherichia coli attachment on simulated plant surface microstructures was studied.
► Silicon structures were microfabricated to mimic stomata, trichomes, and grooves.
► Arrays of trichomes had fewer attached bacteria than arrays of stomata or grooves.
► More bacteria attached around the base of the trichomes than areas further away.
► More bacteria attached close to the stomatal opening than in other areas.