Leaf Surface Topography Contributes to the Ability of Escherichia coli on Leafy Greens to Resist Removal by Washing, Escape Disinfection With Chlorine, and Disperse Through Splash

• Published in: Frontiers in microbiology Vol. 11; p. 1485
• Main Authors: Doan, Hung K, Antequera-Gómez, María L, Parikh, Atul N, Leveau, Johan H J
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 17.07.2020
• Subjects: food safety; leaf replicasting; Microbiology; PDMS; phyllosphere; phyllotelma; topomimetic; food safety; phyllotelma; phyllosphere; PDMS; leaf replicasting; topomimetic
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2020.01485

The attachment of foodborne pathogens to leaf surfaces is a complex process that involves multiple physical, chemical, and biological factors. Here, we report the results from a study designed to specifically determine the contribution of spinach leaf surface topography as it relates to leaf axis (abaxial and adaxial) and leaf age (15, 45, and 75 days old) to the ability of to resist removal by surface wash, to avoid inactivation by chlorine, and to disperse through splash impact. We used fresh spinach leaves, as well as so-called "replicasts" of spinach leaf surfaces in the elastomer polydimethylsiloxane to show that leaf vein density correlated positively with the failure to recover from surfaces, not only using a simple water wash and rinse, but also a more stringent wash protocol involving a detergent. Such failure was more pronounced when was surface-incubated at 24°C compared to 4°C, and in the presence, rather than absence, of nutrients. Leaf venation also contributed to the ability of to survive a 50 ppm available chlorine wash and to laterally disperse by splash impact. Our findings suggest that the topographical properties of the leafy green surface, which vary by leaf age and axis, may need to be taken into consideration when developing prevention or intervention strategies to enhance the microbial safety of leafy greens.