Infiltration of Tomatoes by Aqueous Bacterial Suspensions

Bartz, Jerry A.

doi:10.1094/phyto-71-515

Cited by 98 publications

(55 citation statements)

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“…In the field, this may occur when rain, dew, or irrigation water collects on the surface of produce or, in the event that fruit falls from trees, as a result of contact with ground water. After harvest, wash and flume waters used to clean fruits and vegetables may provide a vehicle to facilitate the infiltration of microbial cells (2,3,27). The potential for infiltration of viable cells is highest if the water is contaminated and antimicrobial agents such as chlorine are ineffective due to low concentration or pH (15).…”

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confidence: 99%

“…The problem of bacterial ingress is exacerbated by differences in water and produce temperatures (2,6). Several researchers have demonstrated that using wash water at a temperature cooler than that of produce (i.e., a negative temperature differential) will result in the absorption of water into tissues (2,3,6,17,27). This phenomenon is predicted from the general gas law.…”

mentioning

confidence: 99%

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Attachment of Escherichia coli O157:H7 to the Surfaces and Internal Structures of Apples as Detected by Confocal Scanning Laser Microscopy

Burnett

Chen

Beuchat

2000

Appl Environ Microbiol

162

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Confocal scanning laser microscopy (CSLM) was used to demonstrate the attachment of Escherichia coli O157:H7 transformed with a plasmid encoding for green fluorescent protein (GFP) to the surface and within the internal structures of nonwaxed Red Delicious cv. apples. Apples at 2 or 25°C were inoculated with an E. coli O157:H7 cell suspension at 2 or 25°C. The effect of a negative temperature differential (cold inoculum, warm apple), a positive differential (warm inoculum, cold apple), and no differential (warm inoculum, warm apple), in combination with a pressure differential (atmospheric versus 10,130 Pa), on the attachment and infiltration of cells was determined. CSLM stereo images of external surfaces of apples subjected to all combinations of test parameters showed preferential cellular attachment to discontinuities in the waxy cuticle on the surface and to damaged tissue surrounding puncture wounds, where the pathogen was observed at depths up to 70 m below the skin surface. Attachment to lenticels was sporadic but was occasionally observed at depths of up to 40 m. Infiltration through the floral tube and attachment to seeds, cartilaginous pericarp, and internal trichomes were observed in all apples examined, regardless of temperature differential during inoculation. The pressure differential had no effect on infiltration or attachment of E. coli O157:H7. Image analysis to count cells at various depths within tissues was used to quantitatively compare the extent of infiltration into various apple structures as well as the effects of the temperature differential. Puncture wounds harbored greater numbers of the pathogen at greater depths than did other sites examined. Attachment or infiltration of cells was greater on the intact skin and in lenticels, russet areas, and the floral tube of apples inoculated under a negative temperature differential compared to those inoculated under no temperature differential. The results suggest that E. coli O157:H7 attached to internal core structures or within tissues of apples may evade decontamination treatments. Interventions designed to deliver disinfectants to these locations or to remove viable cells of E. coli O157:H7 and other pathogens from apples by other means need to be developed and validated.

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mentioning

confidence: 99%

mentioning

confidence: 99%

Attachment of Escherichia coli O157:H7 to the Surfaces and Internal Structures of Apples as Detected by Confocal Scanning Laser Microscopy

Burnett

Chen

Beuchat

2000

Appl Environ Microbiol

162

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“…The internal environment of the plant would provide a more static environment for Salmonella spp, but internalization of human pathogens into plant tissue seems to be a passive process. 30,45 Stomatal openings on the leaf surface naturally allow access to the internal plant environment. Salmonella spp may be attracted to the open stomata during photosynthesis, when sugars are produced at these sites.…”

Section: Resultsmentioning

confidence: 99%

“…30 The immersion of warm fieldgrown tomatoes in cool water in a flume system may also cause the internalization of water as the plant cells contract at the stem scar of the tomato. 45 This has led to the process of heating dunk tank water 10°F above the temperature of the tomato pulp. 47 The bacterial contaminants in the water may become internalized in the fruit, and once internalized, there is no effective sanitizing treatment to remove the Salmonella spp contamination.…”

confidence: 99%

“…The use of contaminated water during processing will introduce pathogens to the produce surface, but may also cause the internalization of pathogens depending on the produce type and water temperature. 30,45 The contact between warm fruit and cool water will cause the plant cells to contract, resulting in the possible internalization of the water. This process has been shown to occur with both mangoes and tomatoes.…”

Section: Contributing Factors To Produce-linked Outbreaksmentioning

confidence: 99%

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