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Siyun Wang
Food, Nutrition and Health, Faculty of Land and Food Systems, The University of British Columbia, Vancouver, BC, Canada

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Review article
Published: 07 June 2021 in PHAGE
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Novel bacteriophages (phages) possessing a broad host range are consistently and routinely reported, yet there is presently no consensus on the definition of “broad host range.” As phages are increasingly being used in the development of methods for the detection and biocontrol of human pathogens, it is important to address the limitations associated with the host range. For instance, unanticipated host range breadth may result in the detection of nonpathogenic targets, thereby increasing the false-positive rate. Moreover, a broad host range is generally favored in biocontrol applications despite the risk of undesirable ancillary effects against nontarget species. Here, we discuss the research progress, applications, and implications of broad host range phages with a focus on tailed broad host range phages infecting human pathogens of concern in the Agri-Food sector.

ACS Style

Karen Fong; Catherine W.Y. Wong; Siyun Wang; Pascal Delaquis. How Broad Is Enough: The Host Range of Bacteriophages and Its Impact on the Agri-Food Sector. PHAGE 2021, 1 .

AMA Style

Karen Fong, Catherine W.Y. Wong, Siyun Wang, Pascal Delaquis. How Broad Is Enough: The Host Range of Bacteriophages and Its Impact on the Agri-Food Sector. PHAGE. 2021; ():1.

Chicago/Turabian Style

Karen Fong; Catherine W.Y. Wong; Siyun Wang; Pascal Delaquis. 2021. "How Broad Is Enough: The Host Range of Bacteriophages and Its Impact on the Agri-Food Sector." PHAGE , no. : 1.

Journal article
Published: 30 May 2021 in Comprehensive Reviews in Food Science and Food Safety
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Listeria monocytogenes continues to pose a food safety risk in ready-to-eat foods, including fresh and soft/semisoft cheeses. Despite L. monocytogenes being detected regularly along the cheese production continuum, variations in cheese style and intrinsic/extrinsic factors throughout the production process (e.g., pH, water activity, and temperature) affect the potential for L. monocytogenes survival and growth. As novel preservation strategies against the growth of L. monocytogenes in susceptible cheeses, researchers have investigated the use of various biocontrol strategies, including bacteriocins and bacteriocin-producing cultures, bacteriophages, and competition with native microbiota. Bacteriocins produced by lactic acid bacteria (LAB) are of particular interest to the dairy industry since they are often effective against Gram-positive organisms such as L. monocytogenes, and because many LAB are granted Generally Regarded as Safe (GRAS) status by global food safety authorities. Similarly, bacteriophages are also considered a safe form of biocontrol since they have high specificity for their target bacterium. Both bacteriocins and bacteriophages have shown success in reducing L. monocytogenes populations in cheeses in the short term, but regrowth of surviving cells can commonly occur in the finished cheeses. Competition with native microbiota, not mediated by bacteriocin production, has also shown potential to inhibit the growth of L. monocytogenes in cheeses, but the mechanisms are still unclear. Here, we have reviewed the current knowledge on the growth of L. monocytogenes in fresh and surface-ripened soft and semisoft cheeses, as well as the various methods used for biocontrol of this common foodborne pathogen.

ACS Style

Justin Falardeau; Aljoša Trmčić; Siyun Wang. The occurrence, growth, and biocontrol of Listeria monocytogenes in fresh and surface‐ripened soft and semisoft cheeses. Comprehensive Reviews in Food Science and Food Safety 2021, 1 .

AMA Style

Justin Falardeau, Aljoša Trmčić, Siyun Wang. The occurrence, growth, and biocontrol of Listeria monocytogenes in fresh and surface‐ripened soft and semisoft cheeses. Comprehensive Reviews in Food Science and Food Safety. 2021; ():1.

Chicago/Turabian Style

Justin Falardeau; Aljoša Trmčić; Siyun Wang. 2021. "The occurrence, growth, and biocontrol of Listeria monocytogenes in fresh and surface‐ripened soft and semisoft cheeses." Comprehensive Reviews in Food Science and Food Safety , no. : 1.

Journal article
Published: 26 February 2021 in Antibiotics
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Antibiotic resistance (AR) phenotypes and acquired resistance determinants (ARDs) detected by in silico analysis of genome sequences were examined in 55 Shiga toxin-producing Escherichia coli (STEC) isolates representing diverse serotypes recovered from surfaces waters and sediments in a mixed use urban/agricultural landscape in British Columbia, Canada. The isolates displayed decreased susceptibility to florfenicol (65.5%), chloramphenicol (7.3%), tetracycline (52.7%), ampicillin (49.1%), streptomycin (34.5%), kanamycin (20.0%), gentamycin (10.9%), amikacin (1.8%), amoxicillin/clavulanic acid (21.8%), ceftiofur (18.2%), ceftriaxone (3.6%), trimethoprim-sulfamethoxazole (12.7%), and cefoxitin (3.6%). All surface water and sediment isolates were susceptible to ciprofloxacin, nalidixic acid, ertapenem, imipenem and meropenem. Eight isolates (14.6%) were multidrug resistant. ARDs conferring resistance to phenicols (floR), trimethoprim (dfrA), sulfonamides (sul1/2), tetracyclines (tetA/B), and aminoglycosides (aadA and aph) were detected. Additionally, narrow-spectrum β-lactamase blaTEM-1b and extended-spectrum AmpC β-lactamase (cephalosporinase) blaCMY-2 were detected in the genomes, as were replicons from plasmid incompatibility groups IncFII, IncB/O/K/Z, IncQ1, IncX1, IncY and Col156. A comparison with surveillance data revealed that AR phenotypes and ARDs were comparable to those reported in generic E. coli from food animals. Aquatic environments in the region are potential reservoirs for the maintenance and transmission of antibiotic resistant STEC, associated ARDs and their plasmids.

ACS Style

Yvonne Ma; Jessica Chen; Karen Fong; Stephanie Nadya; Kevin Allen; Chad Laing; Kim Ziebell; Ed Topp; Laura Carroll; Martin Wiedmann; Pascal Delaquis; Siyun Wang. Antibiotic Resistance in Shiga Toxigenic Escherichia coli Isolates from Surface Waters and Sediments in a Mixed Use Urban Agricultural Landscape. Antibiotics 2021, 10, 237 .

AMA Style

Yvonne Ma, Jessica Chen, Karen Fong, Stephanie Nadya, Kevin Allen, Chad Laing, Kim Ziebell, Ed Topp, Laura Carroll, Martin Wiedmann, Pascal Delaquis, Siyun Wang. Antibiotic Resistance in Shiga Toxigenic Escherichia coli Isolates from Surface Waters and Sediments in a Mixed Use Urban Agricultural Landscape. Antibiotics. 2021; 10 (3):237.

Chicago/Turabian Style

Yvonne Ma; Jessica Chen; Karen Fong; Stephanie Nadya; Kevin Allen; Chad Laing; Kim Ziebell; Ed Topp; Laura Carroll; Martin Wiedmann; Pascal Delaquis; Siyun Wang. 2021. "Antibiotic Resistance in Shiga Toxigenic Escherichia coli Isolates from Surface Waters and Sediments in a Mixed Use Urban Agricultural Landscape." Antibiotics 10, no. 3: 237.

Journal article
Published: 23 February 2021 in mSystems
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Warm, humid, and nutrient-rich conditions that are used to produce sprouts encourage Salmonella enterica to proliferate. However, many disparate sanitation methods exist, and there is currently no single treatment that can guarantee pathogen-free seeds.

ACS Style

Ga-Hee Ban; Yue Dai; Tao Huan; Alfred Ke; Pascal Delaquis; Siyun Wang. Endogenous Metabolites Released by Sanitized Sprouting Alfalfa Seed Inhibit the Growth of Salmonella enterica. mSystems 2021, 6, 1 .

AMA Style

Ga-Hee Ban, Yue Dai, Tao Huan, Alfred Ke, Pascal Delaquis, Siyun Wang. Endogenous Metabolites Released by Sanitized Sprouting Alfalfa Seed Inhibit the Growth of Salmonella enterica. mSystems. 2021; 6 (1):1.

Chicago/Turabian Style

Ga-Hee Ban; Yue Dai; Tao Huan; Alfred Ke; Pascal Delaquis; Siyun Wang. 2021. "Endogenous Metabolites Released by Sanitized Sprouting Alfalfa Seed Inhibit the Growth of Salmonella enterica." mSystems 6, no. 1: 1.

Journal article
Published: 01 January 2021 in Food Quality and Safety
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Stability assessment of observed tolerance phenotypes is integral in understanding stress adaptation in food-borne pathogens. Therefore, the current work was carried out to determine whether ethanol adaptation induced by exposure to 5 per cent ethanol for 60 min is a stable phenomenon in Salmonella enterica serovar Enteritidis. The capacity of Salmonella Enteritidis (S. Enteritidis) to maintain the acquired ethanol adaptation in the absence of sublethal ethanol stress was investigated at 37 °C, 25 °C or 4 °C in Luria–Bertani broth and two types of meat juice. It was found that ethanol adaptation was completely reversed within 40 min at 37 °C or within 60 min at 25 °C, but was stable at 4 °C for at least 48 h in the broth assay. Ethanol adaptation was retained in chicken juice during 60-min incubation at 25 °C or 48-h incubation at 4 °C. Moreover, exposure to pork juice stored at either 25 °C or 4 °C significantly (P<0.05) increased the ethanol tolerance of ethanol-adapted cells. Collectively, these findings suggest that ethanol adaptation stability in S. Enteritidis under cold conditions and in meat juices should be taken into account when conducting a comprehensive risk analysis during food processing.

ACS Style

Shoukui He; Karen Fong; Siyun Wang; Xianming Shi. Meat juice contributes to the stability of ethanol adaptation in Salmonella enterica serovar Enteritidis. Food Quality and Safety 2021, 5, 1 .

AMA Style

Shoukui He, Karen Fong, Siyun Wang, Xianming Shi. Meat juice contributes to the stability of ethanol adaptation in Salmonella enterica serovar Enteritidis. Food Quality and Safety. 2021; 5 ():1.

Chicago/Turabian Style

Shoukui He; Karen Fong; Siyun Wang; Xianming Shi. 2021. "Meat juice contributes to the stability of ethanol adaptation in Salmonella enterica serovar Enteritidis." Food Quality and Safety 5, no. : 1.

Journal article
Published: 14 August 2020 in Colloids and Surfaces B: Biointerfaces
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In food safety and food quality, biofilm research is of great importance for mitigating food-borne pathogens in food processing environments. To supplement the traditional staining techniques for biofilm characterization, we introduce several non-traditional imaging methods for detecting biofilm attachment to the solid–liquid and air–liquid interfaces. For strains of Pseudomonas aeruginosa (the positive control), Acinetobacter baumanii, Listeria monocytogenes and Salmonella enterica, the traditional crystal violet assay showed evidence of biofilm attachment to the well plate base as well as inferred the presence of an air–liquid biofilm attached on the upper well walls where the meniscus was present. However, air–liquid biofilms and solid-surface-attached biofilms were not detected for all of these strains using the non-traditional imaging methods. For L. monocytogenes, we were unable to detect biofilms at a particle-laden, air–liquid interface as evidenced through microscopy, which contradicts the meniscus staining test and suggests that the coffee-ring effect may lead to false positives when using meniscus staining. Furthermore, when L. monocytogenes was cultivated in a pendant droplet in air, only microbial sediment at the droplet apex was observed without any apparent bacterial colonization of the droplet surface. All other strains showed clear evidence of air–liquid biofilms at the air–liquid interface of a pendant droplet. To non-invasively detect if and when air–liquid pellicles form in a well plate, we also present a novel in situ reflection assay that demonstrates the capacity to do this quantitatively.

ACS Style

Abner L. Bogan; Karen Fong; Aljosa Trmcic; Siyun Wang; John M. Frostad. Evaluation of non-traditional visualization methods to detect surface attachment of biofilms. Colloids and Surfaces B: Biointerfaces 2020, 196, 111320 .

AMA Style

Abner L. Bogan, Karen Fong, Aljosa Trmcic, Siyun Wang, John M. Frostad. Evaluation of non-traditional visualization methods to detect surface attachment of biofilms. Colloids and Surfaces B: Biointerfaces. 2020; 196 ():111320.

Chicago/Turabian Style

Abner L. Bogan; Karen Fong; Aljosa Trmcic; Siyun Wang; John M. Frostad. 2020. "Evaluation of non-traditional visualization methods to detect surface attachment of biofilms." Colloids and Surfaces B: Biointerfaces 196, no. : 111320.

Journal article
Published: 01 June 2020 in PHAGE
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Background: Poultry products are the largest food category linked to salmonellosis in Canada. Bacteriophages (phages) have been proposed as a novel antimicrobial in the poultry industry due to their documented ubiquity, efficacy, and safety benefits.Materials and Methods: A library of 78 lytic phages was rapidly screened against 50 prominent poultry-associated Salmonella enterica isolates procured from British Columbia, Canada.Results: A phage cocktail was successfully formulated using only three sewage-isolated phages (SE4, SE13, and SE20) to achieve broad-spectrum antimicrobial efficacy across all S. enterica serovars. Highly promising phages were also characterized using one-step growth curves and transmission electron microscopy.Conclusion: Relative host efficiency is a new agar-based semiquantitative metric developed here for the rapid comparison of different phages against a panel of known bacterial targets.

ACS Style

Thomas Brenner; Karen Fong; Spencer Lee; Siyun Wang. A Dynamic Method for Broad-Spectrum Bacteriophage Cocktail Formulation Against Poultry-Associated Salmonella enterica. PHAGE 2020, 1, 109 -117.

AMA Style

Thomas Brenner, Karen Fong, Spencer Lee, Siyun Wang. A Dynamic Method for Broad-Spectrum Bacteriophage Cocktail Formulation Against Poultry-Associated Salmonella enterica. PHAGE. 2020; 1 (2):109-117.

Chicago/Turabian Style

Thomas Brenner; Karen Fong; Spencer Lee; Siyun Wang. 2020. "A Dynamic Method for Broad-Spectrum Bacteriophage Cocktail Formulation Against Poultry-Associated Salmonella enterica." PHAGE 1, no. 2: 109-117.

Review
Published: 10 April 2020 in Critical Reviews in Food Science and Nutrition
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Foodborne pathogens possess the ability to develop adaptive responses to sublethal environmental stresses, leading to increased tolerance to homologous or heterologous stressing agents commonly applied during food manufacturing. This phenomenon may counteract the effectiveness of current intervention strategies to ensure food safety, thus increasing consumer risk. Foodborne pathogens encounter ethanol, a common food component and a widely used food processing agent, in a variety of niches during their life cycles. The present contribution provides an overview of the influence of adaptation to sublethal doses of ethanol on the stress tolerance of major foodborne pathogens (e.g. Salmonella enterica, Vibrio parahaemolyticus, Listeria monocytogenes, Bacillus cereus, and Cronobacter sakazakii). Fundamental studies on ethanol adaptation mechanisms with a focus on cell membrane properties, gene expression patterns, protein profiles, and mutagenic analyses are discussed. Furthermore, knowledge gaps on effective mitigation of ethanol adaptation in foodborne pathogens are identified and addressed.

ACS Style

Shoukui He; Karen Fong; Siyun Wang; Xianming Shi. Ethanol adaptation in foodborne bacterial pathogens. Critical Reviews in Food Science and Nutrition 2020, 61, 777 -787.

AMA Style

Shoukui He, Karen Fong, Siyun Wang, Xianming Shi. Ethanol adaptation in foodborne bacterial pathogens. Critical Reviews in Food Science and Nutrition. 2020; 61 (5):777-787.

Chicago/Turabian Style

Shoukui He; Karen Fong; Siyun Wang; Xianming Shi. 2020. "Ethanol adaptation in foodborne bacterial pathogens." Critical Reviews in Food Science and Nutrition 61, no. 5: 777-787.

Journal article
Published: 10 March 2020 in International Journal of Molecular Sciences
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Bacteriophages have shown promise as therapeutic alternatives to antibiotics for the control of infectious bacteria, including the human pathogen Salmonella. However, the development of effective phage-based applications requires the elucidation of key interactions between phages and target hosts, particularly since host resistance to phage is inevitable. Little is known about the alteration of host phenotypes following the development of resistance to phage. The aim of this study is to evaluate the antibiotic susceptibility and virulence of a Salmonella isolate following the development of resistance to bacteriophage SI1. We observed enhanced susceptibility to tetracycline and decreased invasion capacity in a differentiated Caco-2 intestinal cell line. Whole genome sequence analysis revealed an array of mutations, most notably, truncations in vgrG1_2, a core gene involved in Type VI secretion and mutations in the lipopolysaccharide, thereby indicating the plausible attachment site of phage SI1. These findings shed light on understanding the underlying mechanism for phage immunity within the host. Importantly, we reveal an associated genetic cost to the bacterial host with developing resistance to phages. Taken together, these results will aid in advancing strategies to delay or eliminate the development of host resistance when designing informed phage-based antimicrobials.

ACS Style

Karen Fong; Kaiwen Mu; Jean-Guillaume Rheault; Roger C. Levesque; David D. Kitts; Pascal Delaquis; Lawrence Goodridge; Siyun Wang. Bacteriophage-Insensitive Mutants of Antimicrobial-Resistant Salmonella Enterica are Altered in their Tetracycline Resistance and Virulence in Caco-2 Intestinal Cells. International Journal of Molecular Sciences 2020, 21, 1883 .

AMA Style

Karen Fong, Kaiwen Mu, Jean-Guillaume Rheault, Roger C. Levesque, David D. Kitts, Pascal Delaquis, Lawrence Goodridge, Siyun Wang. Bacteriophage-Insensitive Mutants of Antimicrobial-Resistant Salmonella Enterica are Altered in their Tetracycline Resistance and Virulence in Caco-2 Intestinal Cells. International Journal of Molecular Sciences. 2020; 21 (5):1883.

Chicago/Turabian Style

Karen Fong; Kaiwen Mu; Jean-Guillaume Rheault; Roger C. Levesque; David D. Kitts; Pascal Delaquis; Lawrence Goodridge; Siyun Wang. 2020. "Bacteriophage-Insensitive Mutants of Antimicrobial-Resistant Salmonella Enterica are Altered in their Tetracycline Resistance and Virulence in Caco-2 Intestinal Cells." International Journal of Molecular Sciences 21, no. 5: 1883.

Journal article
Published: 07 February 2020 in Journal of Food Protection
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Canadian First Nations communities rely on traditional preservation methods such as the smoking, drying, and canning of fish and game meats to ensure long-term food security. Unlike commercial food production, there are no recognized official standards for these methods, rendering their efficacy in producing microbiologically safe foods relatively unknown. In this study, 81 fresh or processed fish and game samples obtained from four British Columbia First Nations communities were analyzed for quality indicator microbes, foodborne pathogens, and mineral levels. Aerobic counts, coliforms (CC), Escherichia coli (EC), lactic acid bacteria, Staphylococcus aureus (STA), and yeast and molds (YM) were enumerated using the TEMPO, whereas the presence of E. coli O157:H7, Listeria monocytogenes, and Salmonella were detected using the VIDAS immunoassay system. The opportunistic pathogens Enterococcus faecalis and Enterococcus faecium were additionally detected using culture methods with subsequent PCR confirmation, and minerals (Ca, Cu, K, Mg, Mn, Na, and Zn) were detected using mass spectrometry. With the exception of STA, microbial loads were significantly (P < 0.05) higher in processed fish and meat samples compared with unprocessed samples, and game samples contained higher microbial levels than fish; however, differences were only significant (P < 0.05) for coliforms, E. coli, and STA. E. coli O157:H7 was detected in one smoked moose sample, and E. faecalis and E. faecium were isolated from 21 and 2 samples, respectively. Although smoked samples contained significantly higher Na levels, they were effective in reducing microbial levels. These results indicate that current food preservation methods practiced by British Columbia First Nations communities are infrequently effective at reducing microbial populations, and in many cases, resulted in increased microbial loads. More efforts should be made to improve the dissemination of safe food handling and processing knowledge to ensure long-term food security and well-being. HIGHLIGHTS

ACS Style

Patricia Hingston; Keely Johnson; David Kitts; Siyun Wang. Safety and Quality of Fish and Game Meats Prepared by First Nations Communities in British Columbia, Canada. Journal of Food Protection 2020, 83, 896 -901.

AMA Style

Patricia Hingston, Keely Johnson, David Kitts, Siyun Wang. Safety and Quality of Fish and Game Meats Prepared by First Nations Communities in British Columbia, Canada. Journal of Food Protection. 2020; 83 (5):896-901.

Chicago/Turabian Style

Patricia Hingston; Keely Johnson; David Kitts; Siyun Wang. 2020. "Safety and Quality of Fish and Game Meats Prepared by First Nations Communities in British Columbia, Canada." Journal of Food Protection 83, no. 5: 896-901.

Journal article
Published: 23 December 2019 in Journal of Food Protection
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Antimicrobial seed treatments recommended by Canadian guidance for sprouted vegetable production (2,000 ppm of hypochlorite for 15 to 20 min or 6 to 10% hydrogen peroxide for 10 min at room temperature) are not fully compliant with organic production principles. We investigated the effect of a sequential treatment consisting of a 10-min soak at 50°C in water followed by exposure to a 2.0% H2O2 plus 0.1% AcOH sanitizing solution against Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica inoculated onto alfalfa and radish seed. The sequential treatment was as effective as the recommended treatments and could reduce populations of all three species by a minimum of 3 log CFU/g using a reduced (1:2) ratio of seed to sanitizing solution and low concentrations of sanitizers approved for use in organic food production. However, the efficacy of all the treatments examined in this work was considerably reduced by storage of the seed for 4 weeks at either 11 or 75% relative humidity prior to treatment and assessment. None of the treatments could eradicate the target pathogens from seed, irrespective of time elapsed since inoculation. The results of this work suggest that the effect of storage should be considered in the assessment of antimicrobial treatments for sprouting vegetable seed. HIGHLIGHTS

ACS Style

Siyun Wang; Jessica Chen; Carmen Wakeling; Susan Bach; Steve Orban; Pascal Delaquis. Disinfection of Alfalfa and Radish Sprouting Seed Using Oxidizing Agents and Treatments Compliant with Organic Food Production Principles. Journal of Food Protection 2019, 83, 779 -787.

AMA Style

Siyun Wang, Jessica Chen, Carmen Wakeling, Susan Bach, Steve Orban, Pascal Delaquis. Disinfection of Alfalfa and Radish Sprouting Seed Using Oxidizing Agents and Treatments Compliant with Organic Food Production Principles. Journal of Food Protection. 2019; 83 (5):779-787.

Chicago/Turabian Style

Siyun Wang; Jessica Chen; Carmen Wakeling; Susan Bach; Steve Orban; Pascal Delaquis. 2019. "Disinfection of Alfalfa and Radish Sprouting Seed Using Oxidizing Agents and Treatments Compliant with Organic Food Production Principles." Journal of Food Protection 83, no. 5: 779-787.

Journal article
Published: 28 November 2019 in Current Research in Food Science
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Salmonella enterica (S. enterica) is a causative agent of multiple outbreaks of foodborne illness associated with fresh produce, including pre-cut melon and leafy vegetables. Current industrial antimicrobial interventions have been shown to reduce microbial populations by 3 log CFU/g and S. Newport S2 by 1 log CFU/g on both lettuce and cantaloupe tissues at all sampling times. In contrast, populations of strains S. Thompson S193 and S194 were reduced by 2 log CFU/g on day 0 on lettuce, but were not significantly different (P > 0.05) from the controls thereafter, S. Newport S195 populations were reduced on lettuce by 1 log CFU/g on day 0 and no reductions were found on cantaloupe tissue. Both aerobic populations and water activity were higher on cantaloupe than on lettuce. The water activity of lettuce decreased significantly (P < 0.05) from 0.845 ± 0.027 on day 0–0.494 ± 0.022 on day 1, but that of cantaloupe remained between 0.977 and 0.993 from day 0–2. The results of this study showed that bacteriophages can reduce S. enterica populations on lettuce and cantaloupe tissues but that the magnitude of the effect was strain-dependent.

ACS Style

Catherine W.Y. Wong; Pascal Delaquis; Lawrence Goodridge; Roger C. Lévesque; Karen Fong; Siyun Wang. Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail. Current Research in Food Science 2019, 2, 25 -32.

AMA Style

Catherine W.Y. Wong, Pascal Delaquis, Lawrence Goodridge, Roger C. Lévesque, Karen Fong, Siyun Wang. Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail. Current Research in Food Science. 2019; 2 ():25-32.

Chicago/Turabian Style

Catherine W.Y. Wong; Pascal Delaquis; Lawrence Goodridge; Roger C. Lévesque; Karen Fong; Siyun Wang. 2019. "Inactivation of Salmonella enterica on post-harvest cantaloupe and lettuce by a lytic bacteriophage cocktail." Current Research in Food Science 2, no. : 25-32.

Journal article
Published: 26 November 2019 in Food Control
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The sanitary status of reusable plastic containers (RPCs) in fresh produce packing/grower operations located in Ontario, British Columbia, and Quebec was evaluated. Visibly soiled, Ready-to-Use, RPCs and those visually clean, were considered sanitary using a criterion of <3 log relative light units (RLU)/100 cm2 in ATP testing, < 4 log colony forming units (CFU)/crate Total Aerobic Count (TAC), <3 log CFU/crate for yeast & mould, and <3 log CFU/crate Enterobacteriaceae, and coliforms along with the absence of Escherichia coli. Collectively, 162 RPCs (48 visibly soiled and 114 visually clean) were sampled with 10% (5/48) of the visibly soiled crates exceeding ATP RLU readings that compares to 81% of clean crates sampled. All visibly soiled crates exceeded the acceptable limits for TAC that compares to 83% of visually clean RPCs. The fail percentage of visibly soiled crates, with respect to Enterobacteriaceae and coliform counts, was 96% (23/24) and 25% (12/48) respectively, compared to 69% (48/70) and 3% (4.4/114) for clean crates. E. coli was recovered from five (3.5%; 5/114) of visually clean RPCs. It was concluded that visual assessment and ATP readings are poor metrics to assess the sanitary status of RPCs. In laboratory trials, Salmonella inoculated onto RPCs declined at a greater rate under low (55%) compared to high (88%) relative humidity (RH). However, the rate of decline of Salmonella was lower if cucumber homogenates were periodically introduced onto the surface of inoculated RPCs with growth occurring under high RH. Transfer of Salmonella from RPC to cucumbers occurred in a diphasic manner with an initial rapid phase followed by a slower rate of attachment with time. Sanitation cycles that included a caustic rinse followed by a peracetic acid treatment supported a 1.0–1.8 log reduction of Salmonella although residual survivors could be transferred from RPCs to cucumbers. The study demonstrated that Salmonella can persist for extended periods on RPCs and then be transferred to produce can occur if crates are inadequately sanitized. This result, coupled with the unsanitary condition of RPCs sampled in the field, reinforces the need to adequately sanitize crates between uses.

ACS Style

Yan Zhu; Fan Wu; Aljosa Trmcic; Siyun Wang; Keith Warriner. Microbiological status of reusable plastic containers in commercial grower/packer operations and risk of Salmonella cross-contamination between containers and cucumbers. Food Control 2019, 110, 107021 .

AMA Style

Yan Zhu, Fan Wu, Aljosa Trmcic, Siyun Wang, Keith Warriner. Microbiological status of reusable plastic containers in commercial grower/packer operations and risk of Salmonella cross-contamination between containers and cucumbers. Food Control. 2019; 110 ():107021.

Chicago/Turabian Style

Yan Zhu; Fan Wu; Aljosa Trmcic; Siyun Wang; Keith Warriner. 2019. "Microbiological status of reusable plastic containers in commercial grower/packer operations and risk of Salmonella cross-contamination between containers and cucumbers." Food Control 110, no. : 107021.

Journal article
Published: 01 October 2019 in International Journal of Food Microbiology
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In this study, we show that growth and prolonged storage of Listeria monocytogenes at 4 °C can promote the selection of variants with enhanced cold and heat tolerance. Enhanced cold-tolerance (ECT) variants (n = 12) were successfully isolated from a strain with impaired cold growth abilities following 84 days of storage at 4 °C in brain heart infusion broth (BHIB). Whole genome sequencing, membrane fatty acid analysis, and stress tolerance profiling were performed on the parent strain and two ECT variants: one displaying regular-sized colonies and the other displaying small colonies when grown at 37 °C on BHI agar. Under cold stress conditions, the parent strain exhibited an impaired ability to produce branched-chain fatty acids which are known to be important for cold adaptation in L.monocytogenes. The ECT variants were able to overcome this limitation, a finding which is hypothesized to be associated with the identification of two independent single-nucleotide polymorphisms in genes encoding subunits of acetyl-coA carboxylase, an enzyme critical for fatty acid biosynthesis. While the ECT phenotype was not found to be associated with improved salt (BHIB + 6% NaCl, 25 °C), acid (BHIB pH 5, 25 °C) or desiccation (33% RH, 20 °C) tolerance, the small-colony variant exhibited significantly (p < 0.05) enhanced heat tolerance at 52 °C in buffered peptone water compared to the parent strain and the other variant. The results from this study demonstrate that the continuous use of refrigeration along the food-supply chain has the potential to select for L.monocytogenes variants with enhanced cold and heat tolerance, highlighting the impact that microbial intervention strategies can have on the evolution of bacterial strains and likewise, food safety.

ACS Style

Patricia A. Hingston; Lisbeth Truelstrup Hansen; Jean-François Pombert; Siyun Wang. Characterization of Listeria monocytogenes enhanced cold-tolerance variants isolated during prolonged cold storage. International Journal of Food Microbiology 2019, 306, 108262 .

AMA Style

Patricia A. Hingston, Lisbeth Truelstrup Hansen, Jean-François Pombert, Siyun Wang. Characterization of Listeria monocytogenes enhanced cold-tolerance variants isolated during prolonged cold storage. International Journal of Food Microbiology. 2019; 306 ():108262.

Chicago/Turabian Style

Patricia A. Hingston; Lisbeth Truelstrup Hansen; Jean-François Pombert; Siyun Wang. 2019. "Characterization of Listeria monocytogenes enhanced cold-tolerance variants isolated during prolonged cold storage." International Journal of Food Microbiology 306, no. : 108262.

Journal article
Published: 01 October 2019 in Applied and Environmental Microbiology
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Stress adaptation in foodborne pathogens has been recognized as a food safety concern since it may compromise currently employed microbial intervention strategies. While adaptation to sublethal levels of ethanol is able to induce ethanol tolerance in foodborne pathogens, the molecular mechanism underlying this phenomenon is poorly characterized. Hence, global proteomic analysis and mutagenic analysis were conducted in the current work to understand the strategies employed by Salmonella enterica subsp. enterica serovar Enteritidis to respond to ethanol adaptation. It was revealed that coordinated regulation of multiple pathways involving metabolism, ABC transporters, regulators, enterobactin biosynthesis and uptake, the ribosome, flagellar assembly, and virulence was responsible for the development of ethanol adaptation response in this pathogen. Such knowledge will undoubtedly contribute to the development and implementation of more-effective food safety interventions.

ACS Style

Shoukui He; Xiaojie Qin; Catherine W. Y. Wong; Chunlei Shi; Siyun Wang; Xianming Shi. Ethanol Adaptation Strategies in Salmonella enterica Serovar Enteritidis Revealed by Global Proteomic and Mutagenic Analyses. Applied and Environmental Microbiology 2019, 85, 1 .

AMA Style

Shoukui He, Xiaojie Qin, Catherine W. Y. Wong, Chunlei Shi, Siyun Wang, Xianming Shi. Ethanol Adaptation Strategies in Salmonella enterica Serovar Enteritidis Revealed by Global Proteomic and Mutagenic Analyses. Applied and Environmental Microbiology. 2019; 85 (19):1.

Chicago/Turabian Style

Shoukui He; Xiaojie Qin; Catherine W. Y. Wong; Chunlei Shi; Siyun Wang; Xianming Shi. 2019. "Ethanol Adaptation Strategies in Salmonella enterica Serovar Enteritidis Revealed by Global Proteomic and Mutagenic Analyses." Applied and Environmental Microbiology 85, no. 19: 1.

Journal article
Published: 14 September 2019 in Viruses
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Phages infecting members of the opportunistic human pathogen, Salmonella enterica, are widespread in natural environments and offer a potential source of agents that could be used for controlling populations of this bacterium; yet, relatively little is known about these phages. Here we describe the isolation and characterization of 45 phages of Salmonella enterica from disparate geographic locations within British Columbia, Canada. Host-range profiling revealed host-specific patterns of susceptibility and resistance, with several phages identified that have a broad-host range (i.e., able to lyse >40% of bacterial hosts tested). One phage in particular, SE13, is able to lyse 51 out of the 61 Salmonella strains tested. Comparative genomic analyses also revealed an abundance of sequence diversity in the sequenced phages. Alignment of the genomes grouped the phages into 12 clusters with three singletons. Phages within certain clusters exhibited extraordinarily high genome homology (>98% nucleotide identity), yet between clusters, genomes exhibited a span of diversity (

ACS Style

Karen Fong; Denise M. Tremblay; Pascal Delaquis; Lawrence Goodridge; Roger C. Levesque; Sylvain Moineau; Curtis A. Suttle; Siyun Wang. Diversity and Host Specificity Revealed by Biological Characterization and Whole Genome Sequencing of Bacteriophages Infecting Salmonella enterica. Viruses 2019, 11, 854 .

AMA Style

Karen Fong, Denise M. Tremblay, Pascal Delaquis, Lawrence Goodridge, Roger C. Levesque, Sylvain Moineau, Curtis A. Suttle, Siyun Wang. Diversity and Host Specificity Revealed by Biological Characterization and Whole Genome Sequencing of Bacteriophages Infecting Salmonella enterica. Viruses. 2019; 11 (9):854.

Chicago/Turabian Style

Karen Fong; Denise M. Tremblay; Pascal Delaquis; Lawrence Goodridge; Roger C. Levesque; Sylvain Moineau; Curtis A. Suttle; Siyun Wang. 2019. "Diversity and Host Specificity Revealed by Biological Characterization and Whole Genome Sequencing of Bacteriophages Infecting Salmonella enterica." Viruses 11, no. 9: 854.

Journal article
Published: 20 July 2019 in Toxins
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Listeria monocytogenes strains are known to harbour plasmids that confer resistance to sanitizers, heavy metals, and antibiotics; however, very little research has been conducted into how plasmids may influence L. monocytogenes’ ability to tolerate food-related stresses. To investigate this, a library (n = 93) of L. monocytogenes plasmid sequences were compared. Plasmid sequences were divided into two groups (G1 and G2) based on a repA phylogeny. Twenty-six unique plasmid types were observed, with 13 belonging to each of the two repA-based groups. G1 plasmids were significantly (p < 0.05) smaller than G2 plasmids but contained a larger diversity of genes. The most prevalent G1 plasmid (57,083 bp) was observed in 26 strains from both Switzerland and Canada and a variety of serotypes. Quantitative PCR (qPCR) revealed a >2-fold induction of plasmid-contained genes encoding an NADH peroxidase, cadmium ATPase, multicopper oxidase, and a ClpL chaperone protein during growth under salt (6% NaCl) and acid conditions (pH 5) and ProW, an osmolyte transporter, under salt stress conditions. No differences in salt and acid tolerance were observed between plasmid-cured and wildtype strains. This work highlights the abundance of specific plasmid types among food-related L. monocytogenes strains, the unique characteristics of G1 and G2 plasmids, and the possible contributions of plasmids to L. monocytogenes tolerance to food-related stresses.

ACS Style

Patricia Hingston; Thomas Brenner; Lisbeth Truelstrup Hansen; Siyun Wang. Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions. Toxins 2019, 11, 426 .

AMA Style

Patricia Hingston, Thomas Brenner, Lisbeth Truelstrup Hansen, Siyun Wang. Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions. Toxins. 2019; 11 (7):426.

Chicago/Turabian Style

Patricia Hingston; Thomas Brenner; Lisbeth Truelstrup Hansen; Siyun Wang. 2019. "Comparative Analysis of Listeria monocytogenes Plasmids and Expression Levels of Plasmid-Encoded Genes during Growth under Salt and Acid Stress Conditions." Toxins 11, no. 7: 426.

Journal article
Published: 24 May 2019 in Journal of Food Protection
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Multiple outbreaks of foodborne illness caused by Salmonella sp. have been linked to fresh produce. Understanding variability in colonization potential is critical for the selection of experimental strains suitable for research on the ecology of the species in growing food plants. The fate of 43 Salmonella strains from 29 serovars was examined on seedlings from two cultivars of lettuce (‘Winter Density’ and ‘Parris Island Cos’) and tomato (‘Amish Paste’ and ‘Manitoba’). Salmonella populations were measured on xylose lysine deoxycholate agar immediately after inoculation and after 5 days of incubation at 21°C. Laser scanning confocal microscopy was also performed to examine the distribution of cells on seedling leaf surfaces. Laser scanning confocal microscopy showed that cells or cellular aggregates were located within stomata, in surface depressions adjacent to stomata, or on random surface locations on seedlings that were successfully colonized. Populations of 26 strains (60.5%) increased on seedlings from all plant species and cultivars, although there were significant differences (P < 0.05) in the extent of population increase achieved by different strains on the same plant species–cultivar combinations. The remaining strains displayed differential ability to colonize seedlings depending on plant species or cultivar. The results of the present study indicate that the colonization potential of Salmonella is highly variable and should be carefully considered in the selection of experimental strains. HIGHLIGHTS

ACS Style

Catherine W. Y. Wong; Siyun Wang; Roger C. Lévesque; Lawrence Goodridge; Pascal Delaquis. Fate of 43 Salmonella Strains on Lettuce and Tomato Seedlings. Journal of Food Protection 2019, 82, 1045 -1051.

AMA Style

Catherine W. Y. Wong, Siyun Wang, Roger C. Lévesque, Lawrence Goodridge, Pascal Delaquis. Fate of 43 Salmonella Strains on Lettuce and Tomato Seedlings. Journal of Food Protection. 2019; 82 (6):1045-1051.

Chicago/Turabian Style

Catherine W. Y. Wong; Siyun Wang; Roger C. Lévesque; Lawrence Goodridge; Pascal Delaquis. 2019. "Fate of 43 Salmonella Strains on Lettuce and Tomato Seedlings." Journal of Food Protection 82, no. 6: 1045-1051.

Journal article
Published: 15 April 2019 in Food Microbiology
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The various stages of the cheese-making process harbor distinct bacterial communities which may influence the sensory characteristics of artisanal cheeses. The objective of this study was to investigate the microbiota from dairy farm to final cheeses along an artisanal cheese-making continuum. Environmental and food samples were collected from 21 sites, including the dairy farm, milk, cheese plant, and finished cheeses. The microbiota of these samples were analyzed using 16S rRNA amplicon sequencing, with sequences grouped into operational taxonomic units (OTUs) by phylotype at the genus level. Alpha diversity decreased from dairy farm to finished cheese. Firmicutes was the dominant phylum, ranging from 31% to 92% between the dairy farm and finished cheeses, respectively, with Proteobacteria, Actinobacteria, and Bacteroides also present (25%, 11%, and 9% overall relative abundance, respectively). Of the 37 core OTUs (>5 reads in >80% of site replicates) observed in cheese, 32 were shared with the dairy farm. Starter-related genera (i.e., Lactococcus, Lactobacillus, Streptococcus, and Leuconostoc) represented between 69% and 98% relative abundance in final cheeses depending on style, with the remainder likely acquired from various environmental sources on the farm and during the cheese-making process.

ACS Style

Justin Falardeau; Kristie Keeney; Aljoša Trmčić; David Kitts; Siyun Wang. Farm-to-fork profiling of bacterial communities associated with an artisan cheese production facility. Food Microbiology 2019, 83, 48 -58.

AMA Style

Justin Falardeau, Kristie Keeney, Aljoša Trmčić, David Kitts, Siyun Wang. Farm-to-fork profiling of bacterial communities associated with an artisan cheese production facility. Food Microbiology. 2019; 83 ():48-58.

Chicago/Turabian Style

Justin Falardeau; Kristie Keeney; Aljoša Trmčić; David Kitts; Siyun Wang. 2019. "Farm-to-fork profiling of bacterial communities associated with an artisan cheese production facility." Food Microbiology 83, no. : 48-58.

Journal article
Published: 01 December 2018 in Food Microbiology
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Mung bean sprouts were implicated in several foodborne outbreaks worldwide in recent years. The objectives of this study were to (i) assess the efficacy of individual (mild heat) and combined treatments (mild heat followed by acetic acid or/and hydrogen peroxide) for the inactivation of enteric bacterial pathogens on mung bean intended for sprout production and (ii) determine the impact of the treatments and storage conditions on germination. Mung bean was co-inoculated with Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes to achieve initial populations of approximately 5-6 log CFU of each species /g bean. The inoculated bean was then subjected to eight different treatments immediately after inoculation and after four weeks of storage at 22°C. Selective media were used to estimate residual populations of each pathogen after treatment and subsequent to germination. The results showed that all combined treatments achieved a minimum 3-log CFU/g reduction in E. coli O157:H7, S. enterica and L. monocytogenes on freshly inoculated bean. The combined treatment with hot water followed by exposure to H2O2 and acetic acid resulted in a > 3-log reduction on mung bean stored for four weeks. The bactericidal effect of the combined treatments was significantly (P < 0.05) impacted by the duration of treatment and bean storage time. These data suggest that the combined use of mild heat, acetic acid and H2O2 may serve as a choice for organic sprouts industry in the disinfection of mung bean.

ACS Style

Monika Trząskowska; Yue Dai; Pascal Delaquis; Siyun Wang. Pathogen reduction on mung bean reduction of Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes on mung bean using combined thermal and chemical treatments with acetic acid and hydrogen peroxide. Food Microbiology 2018, 76, 62 -68.

AMA Style

Monika Trząskowska, Yue Dai, Pascal Delaquis, Siyun Wang. Pathogen reduction on mung bean reduction of Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes on mung bean using combined thermal and chemical treatments with acetic acid and hydrogen peroxide. Food Microbiology. 2018; 76 ():62-68.

Chicago/Turabian Style

Monika Trząskowska; Yue Dai; Pascal Delaquis; Siyun Wang. 2018. "Pathogen reduction on mung bean reduction of Escherichia coli O157:H7, Salmonella enterica and Listeria monocytogenes on mung bean using combined thermal and chemical treatments with acetic acid and hydrogen peroxide." Food Microbiology 76, no. : 62-68.