Effects of Cell Surface Charge and Hydrophobicity on Attachment of 16 Salmonella Serovars to Cantaloupe Rind and Decontamination with Sanitizers†

Adherence of bacteria to cantaloupe rind is favored by surface irregularities such as roughness, crevices, and pits, thus reducing the ability of washing or sanitizer treatments to remove or inactivate attached cells. In this study, we compared the surface charge and hydrophobicity of two cantaloupe-related outbreak strains of Salmonella Poona (RM2350 and G-91-1595) to those of 14 additional Salmonella strains using electrostatic and hydrophobic interaction chromatography. The relative abilities of the 16 strains to attach to cantaloupe surfaces and resist removal by washing with water, chlorine (200 ppm), or hydrogen peroxide (2.5%) for 5 min after a storage period of up to 7 days at 5 to 20°C also were determined. Whole cantaloupes were inoculated with each pathogen at 8.36 log CFU/ml, dried for 1 h inside a biosafety cabinet, stored, and then subjected to the washing treatments. Only the positive surface charge of the two cantaloupe-related strains of Salmonella Poona was significantly higher (P < 0.05) than that of the other strains. Initial bacterial attachment to cantaloupe surfaces ranged from 3.68 to 4.56 log CFU/cm2 (highest values for Salmonella Michigan, Newport, Oranienburg, and Mbandaka). The average percentage of the total bacterial population strongly attached to the cantaloupe surface for the Salmonella serovars studied ranged from 0.893 to 0.946 at 5°C and from 0.987 to 0.999 at 25°C. Washing inoculated melons with water did not produce a significant reduction in the concentration of the pathogens (P > 0.05). Chlorine and hydrogen peroxide treatments caused an average 3-log reduction when applied 20 to 40 min postinoculation. However, sanitizer treatments applied 60 min or more postinoculation were less effective (approximately 2.5-log reduction). No significant differences were noted in sanitizer efficacy against the individual strains (P > 0.05). The two cantaloupe-related outbreak Salmonella Poona strains did not significantly differ from the other Salmonella strains tested in negative cell surface charge or hydrophobicity, were not more effective in attaching to whole melon surfaces, and were not more resistant to the various washing treatments when present on rinds.

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Salmonella Sofia Differs from Other Poultry-Associated Salmonella Serovars with Respect to Cell Surface Hydrophobicity

Journal of Food Protection ◽

10.4315/0362-028x-71.12.2421 ◽

2008 ◽

Vol 71 (12) ◽

pp. 2421-2428 ◽

Cited By ~ 18

Author(s):

T. W. R. CHIA ◽

N. FEGAN ◽

T. A. McMEEKIN ◽

G. A. DYKES

Keyword(s):

Zeta Potential ◽

Cell Surface ◽

Physicochemical Properties ◽

Surface Charge ◽

Hydrophobic Interaction ◽

Salmonella Enterica ◽

Food System ◽

Cell Surface Hydrophobicity ◽

Bacterial Attachment ◽

Salmonella Serovars

Salmonella enterica is one of the most important foodborne pathogens. Salmonella enterica subsp. II 4,12:b:– (Salmonella Sofia) is commonly found in Australian poultry. It has been suggested that physicochemical properties such as surface charge and hydrophobicity may affect bacterial attachment to surfaces and their ability to persist in food systems. A possible link between hydrophobicity cell surface charge and persistence of Salmonella from the poultry system was examined. Hydrophobicity of Salmonella Sofia (n = 14), Salmonella Typhimurium (n = 6), Salmonella Infantis (n = 3), and Salmonella Virchow (n = 2) was assayed using hydrophobic interaction chromatography, bacterial adherence to hydrocarbons (BATH), using xylene or hexadecane, and the contact angle method (CAM). Cellular surface charge (CSC) of the isolates was determined using zeta potential measurements. The majority (12 of 14) of Salmonella Sofia isolates were found to be hydrophobic when assayed using BATH with xylene, except isolates S1635 and S1636, and the other serovars were found to be hydrophilic. Salmonella Sofia isolates were not significantly different (P > 0.05) from isolates of other serovars as measured by hydrophobic interaction, BATH with hexadecane, or the CAM. No significant differences (P > 0.05) in zeta potential measurements were observed between isolates. Principal component analysis using results from all four measures of hydrophobicity allowed clear differentiation between isolates of the serovar Salmonella Sofia (except S1635 and S1636) and those of other Salmonella serovars. Differences in physicochemical properties may be a contributing factor to the Salmonella Sofia serovar's ability to attach to surfaces and persist in a food system.

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Relationship between the Physicochemical Properties of Nonchitinolytic Listeria and Salmonella and Their Attachment to Shrimp Carapace

Journal of Food Protection ◽

10.4315/0362-028x-72.6.1181 ◽

2009 ◽

Vol 72 (6) ◽

pp. 1181-1189 ◽

Cited By ~ 8

Author(s):

M. N. WAN NORHANA ◽

REBECCA M. GOULTER ◽

SUSAN E. POOLE ◽

HILTON C. DEETH ◽

GARY A. DYKES

Keyword(s):

Cell Surface ◽

Physicochemical Properties ◽

Surface Charge ◽

Foodborne Pathogens ◽

Bacterial Species ◽

Chitinase Activity ◽

Bacterial Attachment ◽

Bacterial Cells ◽

Production Chain ◽

Cell Surface Charge

Listeria and Salmonella are important foodborne pathogens normally associated with the shrimp production chain. This study investigated the potential of Salmonella Typhimurium, Salmonella Senftenberg, and Listeria monocytogenes (Scott A and V7) to attach to and colonize shrimp carapace. Attachment and colonization of Listeria and Salmonella were demonstrated. Shrimp abdominal carapaces showed higher levels of bacterial attachment (P < 0.05) than did head carapaces. Listeria consistently exhibited greater attachment (P < 0.05) than did Salmonella on all surfaces. Chitinase activity of all strains was tested and found not to occur at the three temperatures (10, 25, and 37°C) tested. The surface physicochemical properties of bacterial cells and shrimp carapace were studied to determine their role in attachment and colonization. Salmonella had significantly (P < 0.05) more positive (−3.9 and −6.0 mV) cell surface charge than Listeria (−18 and −22.8 mV) had. Both bacterial species were found to be hydrophilic (<35%) when measured by the bacterial adherence to hydrocarbon method and by contact angle (θ) measurements (Listeria, 21.3 and 24.8°, and Salmonella, 14.5 and 18.9°). The percentage of cells retained by Phenyl-Sepharose was lower for Salmonella (12.8 to 14.8%) than it was for Listeria (26.5 to 31.4%). The shrimp carapace was found to be hydrophobic (θ = 74.5°), and a significant (P < 0.05) difference in surface roughness between carapace types was noted. There was a linear correlation between bacterial cell surface charge (r2 = 0.95) and hydrophobicity (r2 = 0.85) and initial attachment (P < 0.05) of Listeria and Salmonella to carapaces. However, the same properties could not be related to subsequent colonization.

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Cell surface charge characteristics and their relationship to bacterial attachment to meat surfaces.

Applied and Environmental Microbiology ◽

10.1128/aem.55.4.832-836.1989 ◽

1989 ◽

Vol 55 (4) ◽

pp. 832-836 ◽

Cited By ~ 268

Author(s):

J S Dickson ◽

M Koohmaraie

Keyword(s):

Cell Surface ◽

Surface Charge ◽

Bacterial Attachment ◽

Cell Surface Charge

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Mapping Surface Charge Distribution of Single-Cell via Charged Nanoparticle

Cells ◽

10.3390/cells10061519 ◽

2021 ◽

Vol 10 (6) ◽

pp. 1519

Author(s):

Leixin Ouyang ◽

Rubia Shaik ◽

Ruiting Xu ◽

Ge Zhang ◽

Jiang Zhe

Keyword(s):

Cell Surface ◽

Charge Density ◽

Surface Charge ◽

Charge Distribution ◽

Surface Charge Density ◽

Single Cells ◽

Fluorescent Light ◽

Fluorescent Nanoparticles ◽

Cell Surface Charge ◽

Surface Charge Distribution

Many bio-functions of cells can be regulated by their surface charge characteristics. Mapping surface charge density in a single cell’s surface is vital to advance the understanding of cell behaviors. This article demonstrates a method of cell surface charge mapping via electrostatic cell–nanoparticle (NP) interactions. Fluorescent nanoparticles (NPs) were used as the marker to investigate single cells’ surface charge distribution. The nanoparticles with opposite charges were electrostatically bonded to the cell surface; a stack of fluorescence distribution on a cell’s surface at a series of vertical distances was imaged and analyzed. By establishing a relationship between fluorescent light intensity and number of nanoparticles, cells’ surface charge distribution was quantified from the fluorescence distribution. Two types of cells, human umbilical vein endothelial cells (HUVECs) and HeLa cells, were tested. From the measured surface charge density of a group of single cells, the average zeta potentials of the two types of cells were obtained, which are in good agreement with the standard electrophoretic light scattering measurement. This method can be used for rapid surface charge mapping of single particles or cells, and can advance cell-surface-charge characterization applications in many biomedical fields.

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