Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce

Ge, Chongtao; Lee, Cheonghoon; Nangle, Ed; Lǐ, Jiànróng; Gardner, D.; Kleinhenz, Matthew D.; Lee, Ji-Young

doi:10.1016/j.ijfoodmicro.2013.10.010

Cited by 18 publications

(23 citation statements)

References 34 publications

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“…Heat and drought applied to lettuce plants individually or in combination for 2 days did not promote the internalization of E. coli O157:H7 from soil into leaves (8). Similarly, the application of flooding or drought stress to lettuce plants for 2 days did not enhance the internalization of Salmonella Typhimurium from leaf surfaces into internal tissues (29).…”

Section: Discussionmentioning

confidence: 93%

“…We followed the same methods for application of the heat, flood, and physical damage stressors reported in previous studies that addressed the effects of these abiotic stressors on human-pathogenic bacteria, such as Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium and evaluated the same parameters (8,9,29). The heat (36°C) and flood stressors were applied for a short duration (2 days), whereas physical damage was limited to bending of the outer leaves only (mimicking the common damage due to animals, farmers, equipment, etc., that occurs in the field).…”

Section: Discussionmentioning

confidence: 99%

“…plastic trays (6 pots per tray; Hummert, Topeka, KS), and ϳ2 liters of water, which was not allowed to come into contact with the leaves, was added to each tray. On the next day, the plants were subjected to the following stressors, as described previously (8,9,29): (i) mechanical damage, whereby 6 outer leaves were bent in half widthwise to crack the central vein while maintaining an adequate water supply to the plants (ϳ2 liters/tray/day); (ii) heat stress, whereby the plants were placed inside a growth chamber at temperatures of 36°C during the daytime and 15°C during the nighttime for 2 days while maintaining an adequate water supply as needed (ϳ3 liters/tray/day); or (iii) flood stress, whereby the plants were subjected to overwatering by maintaining ϳ6 liters of water per tray for 2 days. Physical damage was applied only to outer leaves to mimic field damage, and heat and flooding stressors were applied only for 2 days to avoid bolting (caused by extended heat) and root suffocation (caused by extended flooding), which result in unmarketable plants.…”

Section: Preparation Of Virusesmentioning

confidence: 99%

“…Physically damaged plants, flooded plants, and control plants (2 liters/tray/day) with no signs of physical damage to the leaves were all held for 2 days at the greenhouse at temperatures of ϳ23°C during the daytime and 15°C during the nighttime and with a 12-h photoperiod. According to Ge et al (29), normal irrigation for lettuce plants is defined as 250 ml per pot per day. We used a similar approach for calculating the volume of water per tray containing 6 pots (i.e., ϳ1.5 liters/tray/ day).…”

Section: Preparation Of Virusesmentioning

confidence: 99%

“…We used a similar approach for calculating the volume of water per tray containing 6 pots (i.e., ϳ1.5 liters/tray/ day). We added an extra 0.5 liter per tray to take into consideration evaporation and the age difference between our plants (6 to 8 weeks old) and those of Ge et al (4 weeks old) (29). Following the stress treatments, the soil water content was measured by obtaining 100-g soil samples from random plant pots.…”

Section: Preparation Of Virusesmentioning

confidence: 99%

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Abiotic Stress and Phyllosphere Bacteria Influence the Survival of Human Norovirus and Its Surrogates on Preharvest Leafy Greens

Esseili

Gao

Tegtmeier

et al. 2016

Appl Environ Microbiol

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Foodborne outbreaks of human noroviruses (HuNoVs) are frequently associated with leafy greens. Because there is no effective method to eliminate HuNoV from postharvest leafy greens, understanding virus survival under preharvest conditions is crucial. The objective of this study was to evaluate the survival of HuNoV and its surrogate viruses, murine norovirus (MNV), porcine sapovirus (SaV), and Tulane virus (TV), on preharvest lettuce and spinach that were subjected to abiotic stress (physical damage, heat, or flood). We also examined the bacteria culturable from the phyllosphere in response to abiotic stress and in relation to viral persistence. Mature plants were subjected to stressors 2 days prior to inoculation of the viruses on leaves. We quantified the viral RNA, determined the infectivity of the surrogates, and performed bacterial counts on postinoculation days (PIDs) 0, 1, 7, and 14. For both plant types, time exerted significant effects on HuNoV, MNV, SaV, and TV RNA titers, with greater effects being seen for the surrogates. Infectious surrogate viruses were undetectable on PID 14. Only physical damage on PID 14 significantly enhanced HuNoV RNA persistence on lettuce, while the three stressors differentially enhanced the persistence of MNV and TV RNA. Bacterial counts were significantly affected by time and plant type but not by the stressors. However, bacterial counts correlated significantly with HuNoV RNA titers on spinach and with the presence of surrogate viruses on both plant types under various conditions. In conclusion, abiotic stressors and phyllosphere bacterial density may differentially influence the survival of HuNoV and its surrogates on lettuce and spinach, emphasizing the need for the use of preventive measures at the preharvest stage.H uman noroviruses (HuNoVs) are the leading cause of acute gastroenteritis and foodborne illnesses in the United States, causing 19 million to 21 million cases, 570 to 800 deaths, and $777 million in health care-associated costs annually (1). These singlestranded RNA viruses belong to the Caliciviridae family and are 28 to 35 nm in diameter and nonenveloped. Although these viruses cause self-limiting gastroenteritis, more serious infections can develop in high-risk groups, such as the elderly and immunocompromised populations (2). The virus is mainly transmitted to humans via the fecal-oral route either by contact with an infected person or fomites or by ingestion of contaminated food and water (2). Leafy greens are frequently associated with HuNoV outbreaks (1) and are globally recognized to be a high priority in terms of the microbial safety of fresh produce (3). Contamination of leafy greens with HuNoVs can occur at any stage along the farm-to-fork chain (3) through a number of sources, including fecally contaminated water used for irrigation, improperly treated sewage sludge used for fertilization, and food harvesters or food handlers who use improper hygiene practices (4, 5). Because HuNoVs have a low infectious dose (ϳ18 to 1,000 viral particles) (6) ...

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Preparation Of Virusesmentioning

confidence: 99%

Section: Preparation Of Virusesmentioning

confidence: 99%

Section: Preparation Of Virusesmentioning

confidence: 99%

See 3 more Smart Citations

Abiotic Stress and Phyllosphere Bacteria Influence the Survival of Human Norovirus and Its Surrogates on Preharvest Leafy Greens

Esseili

Gao

Tegtmeier

et al. 2016

Appl Environ Microbiol

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Impact of Climate Change and Climate Variability on Food Safety and Occurrence of Foodborne Diseases

Duchenne

Ranghoo-Sanmukhiya

Neetoo

2021

Food Security and Safety

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Internalization and dissemination of human norovirus and Tulane virus in fresh produce is plant dependent

et al. 2018

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Human norovirus (NoV) is a leading cause of fresh produce associated outbreaks. Previous research indicates that the roots of growing leafy greens and berries internalize human NoV. However the effect of plant type and inoculum level on internalization rates has not been directly compared. In this study we compared the internalization and dissemination rates of human NoV and its surrogate, Tulane virus (TV) in green onion, radishes, and Romaine lettuce. We also evaluated the effect inoculum level and plant growth matrix on the rate of viral internalization. In the hydroponic growth system, we detected internalization and dissemination of human NoV RNA in green onions. In hydroponically growing green onions inoculated with high titer TV, we found higher rates of internalization and dissemination compared to green onions inoculated with low titer TV. In soil growth systems, no infectious TV was detected in either green onion or radishes. However, in Romaine lettuce plants grown in soil approximately 4 log PFU/g was recovered from all tissues on day 14 p.i. Overall, we found that the type of plant, growth matrix, and the inoculum level influences the internalization and dissemination of human NoV and TV.

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Impact of phytopathogen infection and extreme weather stress on internalization of Salmonella Typhimurium in lettuce

Cited by 18 publications

References 34 publications

Abiotic Stress and Phyllosphere Bacteria Influence the Survival of Human Norovirus and Its Surrogates on Preharvest Leafy Greens

Abiotic Stress and Phyllosphere Bacteria Influence the Survival of Human Norovirus and Its Surrogates on Preharvest Leafy Greens

Impact of Climate Change and Climate Variability on Food Safety and Occurrence of Foodborne Diseases

Internalization and dissemination of human norovirus and Tulane virus in fresh produce is plant dependent

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