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Focus on Microbial Food Safety: is it really worth washing leafy greens?
Year:
2014
Source of publication :
Volcani Voice
Authors :
Sela, Shlomo
;
.
Volume :
1 (1)
Co-Authors:
Facilitators :
From page:
16
To page:
19
(
Total pages:
4
)
Abstract:

Fresh or minimally processed ready to eat fruits and vegetables are perceived by consumers as being healthy, tasty, and convenient. Nevertheless, the last few decades have witnessed increased illness following consumption of contaminated fresh- or minimally processed produce. Unlike other types of foods which can undergo thermal process, such as pasteurization or cooking, Ready-to-eat minimally processed fruits and vegetables pose a challenge to the food industry, since current disinfection technologies can not completely eliminate foodborne pathogens. Consequently, the agro-food sector is now searching for alternative means to minimize produce contamination. As part of this effort, studies in Prof. Sela laboratory are aimed at elucidating potential mechanisms of produce contamination. During a study on the attachment of Salmonella (a food-borne bacterial pathogen) to leaf surface of iceberg lettuce, Dr. Yulia Krouptiski (at that time a PhD student at Prof. Sela lab) who led the project, together with Eddy Belausov, a confocal microscopy specialist, have noticed that fluorescent-tagged bacteria were moving on the leaf surface toward special openings called stomata. These openings participate in gas exchange between the interior and exterior of the plant and enables respiration and photosynthesis. Salmonella did not only aggregated near stomata but also penetrated into the interior of the leaf, a protected environment, rich in water and nutrient ingredients that favor bacterial survival. Further studies have revealed that Salmonella internalization is regulated by both plant- and bacterial factors. It seems that the pathogen is attracted to sugars produce by chlorophyll-containing cells at the interior of the leaf tissue, which serve as a delicious food for bacteria, as well. Genetic analysis revealed that the pathogen perceive the presence of sugars within the leaf tissue by a unique chemotaxis system, which directs its movement toward the sugars through the open stomata. Movement of the bacteria is mediated by specific motility organelles called flagella. Additional experiments showed that Salmonella internalization vary greatly between different leafy vegetables and even between cultivars of the same plant. These findings shed a new light on a new contamination route through leaf internalization, which provides the human pathogen with a rich and physical-protected micro-environment. The discovery has important implication to the safety of leafy vegetables as internalized bacteria are much more persistent and resist washing and disinfection compared to surface-attached bacteria. Further studies are conducted to search for new intervening approaches to enhance the microbial safety of leafy vegetables.

Note:
Related Files :
bacteria
food adulteration
Food Contamination
food microbiology
food safety
leafy vegetable
Salmonella
vegetables
Show More
Related Content
More details
DOI :
Article number:
0
Affiliations:
Database:
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
55664
Last updated date:
02/03/2022 17:27
Creation date:
20/07/2021 08:22
You may also be interested in
Scientific Publication
Focus on Microbial Food Safety: is it really worth washing leafy greens?
1 (1)
Focus on Microbial Food Safety: is it really worth washing leafy greens?

Fresh or minimally processed ready to eat fruits and vegetables are perceived by consumers as being healthy, tasty, and convenient. Nevertheless, the last few decades have witnessed increased illness following consumption of contaminated fresh- or minimally processed produce. Unlike other types of foods which can undergo thermal process, such as pasteurization or cooking, Ready-to-eat minimally processed fruits and vegetables pose a challenge to the food industry, since current disinfection technologies can not completely eliminate foodborne pathogens. Consequently, the agro-food sector is now searching for alternative means to minimize produce contamination. As part of this effort, studies in Prof. Sela laboratory are aimed at elucidating potential mechanisms of produce contamination. During a study on the attachment of Salmonella (a food-borne bacterial pathogen) to leaf surface of iceberg lettuce, Dr. Yulia Krouptiski (at that time a PhD student at Prof. Sela lab) who led the project, together with Eddy Belausov, a confocal microscopy specialist, have noticed that fluorescent-tagged bacteria were moving on the leaf surface toward special openings called stomata. These openings participate in gas exchange between the interior and exterior of the plant and enables respiration and photosynthesis. Salmonella did not only aggregated near stomata but also penetrated into the interior of the leaf, a protected environment, rich in water and nutrient ingredients that favor bacterial survival. Further studies have revealed that Salmonella internalization is regulated by both plant- and bacterial factors. It seems that the pathogen is attracted to sugars produce by chlorophyll-containing cells at the interior of the leaf tissue, which serve as a delicious food for bacteria, as well. Genetic analysis revealed that the pathogen perceive the presence of sugars within the leaf tissue by a unique chemotaxis system, which directs its movement toward the sugars through the open stomata. Movement of the bacteria is mediated by specific motility organelles called flagella. Additional experiments showed that Salmonella internalization vary greatly between different leafy vegetables and even between cultivars of the same plant. These findings shed a new light on a new contamination route through leaf internalization, which provides the human pathogen with a rich and physical-protected micro-environment. The discovery has important implication to the safety of leafy vegetables as internalized bacteria are much more persistent and resist washing and disinfection compared to surface-attached bacteria. Further studies are conducted to search for new intervening approaches to enhance the microbial safety of leafy vegetables.

Scientific Publication
You may also be interested in