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Mechanistic understanding of light-driven active internalization of bacteria into leafy greens

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  2018 ASABE Annual International Meeting  1800297.(doi:10.13031/aim.201800297)
Authors:   Mohsen Ranjbaran, Ashim K. Datta
Keywords:   Chemotaxis, internalization, food safety, fresh produce, photosynthesis.

Abstract. Along with an ever- increasing consumption of fresh produce, reported outbreaks of foodborne illnesses linked to fresh produce have been on the rise. Light is one of the factors that can play a role in bacteria infiltration into leafy greens by keeping stomata open and providing photosynthetic nutrients for microorganisms. Despite the known infiltration risks, limited mechanistic knowledge regarding this important infiltration pathway is available. In this work, by looking at one stomatal opening, we model chemotactic transport of bacteria within a leaf tissue in response to the photosynthesis occurred within plant mesophyll and guard cells. The model includes transport of carbon dioxide, oxygen, sugar, and bacteria within the leaf tissue. In addition, biological processes of carbon fixation in chloroplasts, and respiration in mitochondria of the plant cells, as well as motility, chemotaxis, and nutrient consumption by bacteria are considered. Our results show that the photosynthetic products, such as sugar (glucose) and oxygen, diffuse within the liquid at the leaf surface. Concentration gradients of nutrients induce bacteria chemotaxis within the liquid, leading to their association around the guard cells and infiltration into the leaf tissue. The model is further used to study the effects of the most important factors contributing in the infiltration of bacteria into the leaf openings. The ability of bacteria to do chemotaxis was a major factor for infiltration.

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