How Salmonella Bacteria Cling to Spinach Without Sugar Signals

Jim Crocker
21st April, 2024

How Salmonella Bacteria Cling to Spinach Without Sugar Signals

Image Source: Natural Science News, 2024

Key Findings

  • Researchers found that a molecule called FimH helps Salmonella stick to spinach leaves
  • Unlike in humans, Salmonella's attachment to spinach doesn't rely on a sugar called mannose
  • A spinach enzyme could be a new target to prevent Salmonella contamination in produce
In recent years, the safety of fresh produce has become a significant public health concern due to the rising number of foodborne illnesses. A notable culprit in these outbreaks is Salmonella, a bacterium that can cause severe gastrointestinal diseases in humans. A critical aspect of Salmonella's life cycle is its ability to attach to and persist on the surfaces of plants, such as spinach leaves, which are often consumed raw. The mechanisms behind this attachment process are not fully understood, but they are key to developing strategies to prevent contamination of fresh foods. A team of researchers from the Wrocław University of Environmental and Life Sciences has shed light on this process in a new study[1]. They focused on a specific part of the Salmonella bacterium called the FimH adhesin. This molecule is found at the tip of hair-like structures called fimbriae, which cover the surface of the bacterium and are known to play a role in its ability to stick to surfaces. Previous studies have shown that these fimbriae are crucial for Salmonella to adhere to various surfaces, including plants[2][3][4]. However, the specifics of how FimH interacts with plant cells were not well understood. The researchers used a variety of sophisticated techniques to investigate how mutations in the Salmonella genome affected the bacterium's ability to stick to spinach leaves. They discovered that FimH is indeed responsible, at least in part, for the adhesion to the leaves. This finding is significant because it suggests that targeting FimH could be a strategy to prevent Salmonella from contaminating spinach and potentially other fresh produce. One of the more surprising findings of the study was that the interaction between FimH and the spinach leaves did not depend on mannose, a type of sugar that FimH typically binds to when the bacteria adhere to human cells. This suggests that the adhesion to plant cells involves different mechanisms than those used to attach to animal hosts. The researchers went on to identify a plant enzyme called endo-1,3-β-d-Glucanase as a potential receptor for FimH on spinach leaves. This interaction was found to be strong and specific, with a dissociation constant in the nanomolar range, indicating a very tight bond. This research builds on earlier findings that have highlighted the complexity of Salmonella's interactions with plants[2][3][4]. For example, previous studies have shown that Salmonella can exploit a variety of surface structures to attach to plants, and that this ability is regulated by a network of genes[3]. The current study expands on this knowledge by identifying a specific interaction between FimH and a plant enzyme, which could be a new target for interventions to reduce the risk of contamination. The implications of this research are significant for public health and the agriculture industry. By understanding the specific interactions that allow Salmonella to adhere to plant surfaces, scientists and food safety experts can develop new strategies to disrupt these processes. This could include breeding or engineering plants that do not express the specific receptors that Salmonella targets, or creating treatments that block the bacteria's ability to adhere to the plants. In conclusion, the study from the Wrocław University of Environmental and Life Sciences provides valuable insights into the interactions between Salmonella and plant surfaces, particularly spinach leaves. By identifying the role of the FimH adhesin and its plant receptor, this research paves the way for new approaches to enhance the safety of fresh produce and protect public health. The study is a step forward in the ongoing effort to understand and combat foodborne pathogens in the environment.

AgricultureHealthPlant Science

References

Main Study

1) It takes two to attach - endo-1,3-β-d-glucanase as a potential receptor of mannose-independent, FimH-dependent Salmonella Typhimurium binding to spinach leaves.

Published 18th April, 2024

https://doi.org/10.1016/j.fm.2024.104519

Related Studies

2) Interrelationships of food safety and plant pathology: the life cycle of human pathogens on plants.

https://doi.org/10.1146/annurev-phyto-081211-172936

3) The role of cellulose and O-antigen capsule in the colonization of plants by Salmonella enterica.

Journal: Molecular plant-microbe interactions : MPMI, Issue: Vol 20, Issue 9, Sep 2007

4) Colonization of tomato plants by Salmonella enterica is cultivar dependent, and type 1 trichomes are preferred colonization sites.

https://doi.org/10.1128/AEM.01661-10


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