Source: UNIVERSITY OF FLORIDA submitted to
IMPROVING THE MICROBIOLOGICAL SAFETY AND QUALITY OF FRESH AND PROCESSED PRODUCE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1005961
Grant No.
(N/A)
Project No.
FLA-LAL-005447
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
May 4, 2015
Project End Date
Feb 28, 2020
Grant Year
(N/A)
Project Director
Danyluk, MI, D..
Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611
Performing Department
Citrus Research and Education Center, Lake Alfred
Non Technical Summary
The US Centers for Disease Control and Prevention (CDC) estimates that each year some 48 million Americans are sickened as a result of foodborne illness, resulting in 128,000 hospitalizations and 3,000 deaths. In addition to human suffering, foodborne illnesses also have a substantial economic impact in the U.S. Based on recent CDC and Produce Safety Project (www.producesafetyproject.org) data, the annual cost of foodborne illnesses in the US is estimated at $89 billion for loss of productivity, other economic losses and medical expenses. Should a Florida producer be involved in litigation following an outbreak where negligence is directly pushed back onto the grower, costs are estimated to exceed $100,000 per case of foodborne illness. An industry need not be directly involved with an outbreak to see the economic consequences of a food safety problem. In 2008, a Salmonella Saintpaul outbreak was erroneously linked to the consumption of Florida tomatoes. Although eventually linked to jalapeno and Serrano peppers from Mexico, the estimated economic impact to the Florida Tomato industry was more than $100 million dollars (http://www.producesafetyproject.org).Despite FDA/USDA guidance, including Good Agricultural Practices (GAPs) during production and harvest, and Good Manufacturing Practices (GMPs) during packing and postharvest treatment, and mandatory Hazard Analysis Critical Control Point (HACCP) for juice production, outbreaks of foodborne illnesses linked to Florida commodities continue. The implementation of these guidelines (GAPs, GMPs, and HACCP) is quickly becoming a non-negotiable requirement to ensure the safety of products for retailers and consumers alike. This has led to a movement towards behavior-based food safety management in food production and processing environments, and away from food safety management systems. Coupled with this is a progression of risk-based evaluations beyond HACCP, to integrate and coordinate food safety activities through all facets of the farm to fork continuum.
Animal Health Component
0%
Research Effort Categories
Basic
20%
Applied
80%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
7120999110010%
7121099110010%
7121119110010%
7121129110010%
7121199110010%
7121219110010%
7121420110010%
7121430110010%
7121469110010%
7121499110010%
Knowledge Area
712 - Protect Food from Contamination by Pathogenic Microorganisms, Parasites, and Naturally Occurring Toxins;

Subject Of Investigation
1119 - Deciduous tree fruits, general/other; 1469 - Solanaceous and related crops, general/other; 1499 - Vegetables, general/other; 1099 - Tropical/subtropical fruit, general/other; 1129 - Berries and cane fruits, general/other; 1430 - Greens and leafy vegetables; 0999 - Citrus, general/other; 1199 - Deciduous and small fruits, general/other; 1219 - Edible tree nuts, general/other; 1420 - Melons;

Field Of Science
1100 - Bacteriology;
Keywords
Goals / Objectives
The overall goal of this project is to provide data related to microbial safety and spoilage risks associated with fresh produce production, packing and handling practices, in addition to fresh cut, processing, retail and consumer practices. This knowledge will enable the fruit, vegetable and nut industries to provide scientific backing to risks of contamination in their production practices and facilities and documentation for methods used to reduce these risks. Additionally, results from this work will allow the food service industry and consumers to determine appropriate responses to reduce risks from consuming these products. Specific objectives include:To conduct surveillance, epidemiological and transfer studies in order to determine the points and sources where foodborne pathogens may be introduced during production and processing of specific fruits, vegetables and nuts, and the effect that varying production, processing, and environmental factors may have on the contamination event.To characterize microbial survival, growth and contamination mechanisms of foodborne pathogens on specific commodities of importance to Florida, and the environment in which they are grown/processed, including microbial interactions within populations.To develop and test mitigation and management strategies to control foodborne pathogen on these products and there surfaces they may come into contact with during production, packing or processingTo evaluate the microbial causes and consequences of spoilage in processed fruit and vegetable products, and potential mitigation strategies to alleviate these causes
Project Methods
Whenever appropriate, standard methods such as those from the Compendium of Methods for the Microbiological Examination of Foods, the U.S. Food and Drug Administration's Bacteriological Analytical Manual (BAM), or other applicable sources (AOAC, USDA, etc.), will be used for the enumeration or identification of foodborne pathogens.Pathogens. Strains that have been associated with outbreaks from the commodity of interest will be used whenever possible. If not possible, other significant pathogenic strains will be selected. These strains are often available in the PIs laboratory. Validated non-pathogenic surrogate species of various microorganisms are also available for those situations where the use of such organisms may be appropriate.Inoculation. Frozen stock cultures of bacterial strains are typically stored in glycerol stock solutions at -80°C. Prior to use strains are streaked onto non-selective media supplemented with selective agents as appropriate. Inocula may be prepared from plate or broth cultures, and may or may not be washed prior to use. Appropriate carrier media will be used for inoculations at volumes, levels and methods typical for the commodity being evaluated. Methods for inoculation of food commodities will vary, as required, to best mimic standard commodity specific criteria and the specific hypothesis-based research questions being addressed.Recovery of Pathogens from Inoculated Samples. Sample sizes, buffering solutions, and maceration methods will vary depending upon commodity and experiment-specific requirements. Enumeration of bacterial pathogens following serial dilutions by standard plating techniques onto selective and non-selective media, Most Probable Number techniques or by more sophisticated molecular techniques are commonly used by project PIs. When samples fall below the limit of detection standard enrichment protocols (FDA BAM or others) will be followed.Recovery of Pathogens from Environmental and Uninoculated Food Sources. Sampling methods to recover pathogens from the environment and foods will vary depending upon the sampling scheme and source as appropriate for the experimental design of the experiment. All attempts will be made by project PIs to not only determine frequency of pathogen isolation, but also concentration of pathogens identified, as concentration is a critical variable required in risk analysis. When appropriate, concentration techniques may be used to evaluate larger than typical sample volumes/weights and enrichment techniques used to evaluate samples when low numbers of cells are present.Evaluate and model the relationship between environmental parameters and indicator/index organisms to the levels of pathogenic microorganisms. Critical to the development of risk-based approaches to food safety is the understanding of how pathogenic microorganism's presence/numbers relate to easy-to-measure physicochemical and microbial indicators. Currently employed standards throughout the food production and manufacturing sectors involve the frequent sampling for various indicator or index organisms. However, while dogma dictates that changes in indicators or indexes result in an increased risk for a product, very little published literature on this topic is available. One of the drawbacks of testing for pathogens or microbial indicators is the interval between testing and the time of result. In many instances, this time delay can range anywhere from 12 to 120 h depending on target organism(s) that are being detected. Obviously the long detection times preclude testing from being used in real time. To address these issues, we propose to evaluate and model these relationships using available and emerging technologies.Understanding prevalence and frequencies of pathogens and antimicrobial resistance within the environment, food products and food production processing, distributions and consumer systems. Also vital to the success of any risk assessment is a comprehensive perception of both concentration and distribution of risk factors, including foodborne pathogens and presence of antimicrobial resistance genes. Much of the currently available prevalence data is lacking critical concentration data, which while difficult to determine, is an essential piece of any risk assessment. These spatial patterns that exist along the farm-to-fork continuum provide insight into current relative risk of food products and production environments, and are a critical starting point against which all risk reduction attempts can be benchmarked. Statistically-sound sampling methods and sample sizes are of fundamental importance to all studies. These issues will be addressed by our plan to evaluate frequencies and concentrations of pathogens and antimicrobial-resistance genes and identify production, manufacturing, distribution or consumer management practices that improve public health by reducing these risks.Persistence, dissemination and traceability of the microorganisms and antimicrobial resistance within the environment, food products and food processing, distribution, and consumer systems. In addition to understanding relationships between indicator organisms and pathogens, and concentration/frequencies of risk factors during food production, of crucial importance is an understanding of how risk factors can vary from the time a food product is conceived to the time it is consummed by a consumer, and how typical industry or consumer practices and handling can influence these risks. While a significant amount of data exists for some commodities, others remain relatively understudied, and handling practices are continually evolving with the industry. For data that do exist, a systematic review to identify critical data gaps and extraction of data for inclusion into comprehensive risk assessments is an opportunity for PIs of this project. While the term "cross-contamination" is often used, and the principle of prevention of cross-contamination taught to all facets of the industry, data to model and understand the fundamental mechanism of cross-contamination, and elucidate novel prevention strategies are lacking.Risk Analysis. This section describes current and planned activities/methods related to the management of microbiological risks associated with foods arising from significant points along the food production and process continuum (e.g., "farm-to-fork"). Major food commodity groups are identified, along with their interaction(s) with novel intervention strategies, and food safety diagnostic technologies. The ultimate goal of these activities is to lower or reduce pathogens in foods and thus concurrently lower risks of foodborne disease. To accomplish the tasks associated with this objective, models and a risk management framework based on commodity-specific flow diagrams and inputs from the first objective will be developed. A key component of this activity will be the use of risk modeling techniques to relate levels of microbial contamination in food to the likelihood of the occurrence of foodborne outbreaks. The information developed using this approach will then be utilized to mitigate risks at specific points along the farm to fork continuum. The data developed using the risk modeling approaches will also lead to the identification of critical data gaps.Models and risk management. Predictive microbiology and quantitative microbial risk assessment (QMRA) are rapidly developing scientific disciplines that use mathematical equations, numerical data, and expert opinion to estimate the presence, survival, growth, and death of microbes in foods. These models allow for the prediction of the safety of a product, based on the entire sequence of events up to consumption. They provide a framework for identifying critical data gaps and evaluating the effectiveness of risk-reduction strategies.

Progress 05/04/15 to 02/28/20

Outputs
Target Audience:Produce researchers and growers,Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Accomplishments by objectives are detailed in annual Reeports.

Publications


    Progress 10/01/18 to 09/30/19

    Outputs
    Target Audience:Produce researchers and growers, Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? Poultry litter is a known source of Salmonella and poses a contamination risk to fresh produce when applied as an untreated biological soil amendment of animal origin. The purpose of this research was to quantify Salmonella prevalence, concentration and diversity in poultry litter throughout the southern United States. Poultry litter was collected from 13 broiler or breeder farms in Alabama (7), Florida (2), Georgia (2), and Texas (2); 10 farms were visited twice. Seven samples (30 g each) from three to four litter piles at every farm were collected. A total of 490 samples were collected from 37 piles. Samples were selectively enriched for Salmonella by cultural methods; presumptive positives were PCR confirmed. The concentration of Salmonella was determined through concurrent enrichment and serial dilution in MPN reservoirs, paused using refrigeration until Salmonella screening was complete. When a sample was confirmed positive, processing of the MPN reservoirs resumed, and presumptive Salmonella PCR confirmed prior to MPN calculations. Salmonella isolates were serotyped and evaluated by PFGE. Salmonella was detected from six farms (46.2%), in 13 piles (35%), and 33 samples (6.7%). The number of positive samples collected from positive piles ranged from 1 to 7 out of 7 collected samples. Salmonella was more prevalent in samples collected in the fall/winter months than the spring/summer. Of farms visited twice, one was positive on both samplings. Concentrations of Salmonella in positive samples ranged from 1.6 to >280,000 MPN/g with a geometric mean and median of 194 and 120 MPN/g, respectively. Serotypes identified included Anatum, Braenderup, Kentucky, Kiambu, Mbandaka, Michigan, Newport, Saintpaul, and Seftenberg. Salmonella was present on half the farms sampled, in less than half of poultry litter samples collected; concentrations were highly variable. Contaminated, untreated, poultry litter may pose a health risk if untreated poultry manure contacts produce and the application-to-harvest interval does not allow for adequate die-off. Limited information on the survival of Salmonella on food contact surfaces during field packing operations exists. The survival of Salmonella on cantaloupe food contact surfaces, using two different inoculation methods, was evaluated. Five food contact surfaces (cotton, nitrile, rubber gloves, cotton rags, and stainless steel) coupons were autoclaved (clean) or rubbed with a cantaloupe leaf for 20s (fouled), and inoculated with a five-strain cocktail of Salmonella (6 log CFU/ml or g). The wet inoculum was spot inoculated (100µl) onto coupons and dried for 1h. The dry inoculum was prepared by mixing aqueous inoculum with sterile sand and drying for 24h at 40°C, then mixing coupon with 100g of sand for 2min. Coupons were held at 35°C (34% RH) for 8h. Samples were stomached for 2 min with 0.1% peptone (100ml), except stainless steel, where a rub-shake-rub was used, and plated onto selective and non-selective media in triplicate experiments with duplicate replicates (n=6). Under all conditions, Salmonella population reductions following a wet inoculum were significantly higher than those following a dry inoculation over 8h (i.e. clean cotton gloves, 3.30 and 0.75 log reduction for wet and dry, respectively). The exception was fouled cotton gloves, wet (0.80 log reduction) and dry (1.32 log reduction). Salmonella population decline on clean surfaces, regardless of inoculum type or material, were greater than fouled surfaces over 8h. For example, reductions on dry rubber glove (1.25 and 0.33 log), and wet nitrile glove (3.02 and 1.0 log) for clean and fouled, respectively. The exception was cotton gloves, clean (0.75 log reduction) and fouled (1.32 log reduction). Population declines for all materials and cleanliness, ranged from 0.33 log reduction (dry fouled rubber gloves) to 3.3 log reduction (wet clean cotton gloves). Inoculum type and surface cleanliness impacts the survival of Salmonella spp. on field pack food contact surfaces. In Florida, the University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) and the Florida Department of Agriculture and Consumer Services (FDACS) collaborated to provide education and outreach through Produce Safety Alliance (PSA) Grower Training Courses and On-Farm Readiness Reviews (OFRR) to assist farmers in meeting the requirements of the Food Safety Modernization Act (FSMA) Produce Safety Rule (PSR). To determine if PSA training was successful in improving the level of knowledge of the PSR and foundational food safety principals that Florida farmers have and to determine the level of farm preparedness for FSMA PSR compliance. A directional dependent samples t-test was used to determine if there was a significant increase in knowledge after completion of the PSA training (n = 754). For the OFRRs (n = 9), qualitative data was submitted anonymously and compiled for percentages. This data was submitted to an online survey developed by the OFRR team through the National Association of State Departments of Agriculture. For PSA training, results showed post-test scores were statistically and significantly higher than pre-test scores (t = 33.25, p < 0.001), indicating a significant increase in knowledge after participation in the training. Out of 25 points, participants scored an average of 16.45 on the pre-test and 20.66 on the post-test. After collecting anonymous data, the three areas farms required the most improvement were health and hygiene, preharvest worker training, and preharvest water. Of the farms that were assessed, 44.44% met the FSMA PSR requirements, 33.33% needed minor improvements, and 22.22% needed significant improvements to meet the PSR requirements. The results of the PSA Grower Training and the OFRR program demonstrated improvement of the knowledge and compliance level of Florida farms regarding the FSMA PSR.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Holat, H., Z. Topalcengiz, and M.D. Danyluk. 2019. Prediction of Salmonella presence and absence in agricultural surface waters by artificial intelligence approaches. Journal of Food Safety. 2019;e12733. DOI: 10.1111/jfs.12733.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Topalcegniz, Z., R. McEgan, and M.D. Danyluk. 2019. Fate of Salmonella spp. in Central Florida surface waters and evaluation of EPA worst case water as standard medium. Journal of Food Protection. 82:916-925
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Topalcengiz, Z. and M.D. Danyluk. 2019. Fate of Generic and Shiga toxin-producing Escherichia coli (STEC) in Central Florida surface waters and evaluation of EPA worst case water as standard medium. Food Research International. 120:322-329
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Brar, P.K., and M.D. Danyluk. 2019. Validation of Enterococcus faecium as a surrogate for Salmonella under different processing conditions for peanuts and pecans. Food Microbiology. 80:9-17.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Narine, L.K., A. Harder, and M.D. Danyluk. 2019. Floridian producers concerns about the Food Safety Modernization Act. Food Protection Trends. 39:237-244.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: Danyluk, M.D., L.M. Friedrich, L.L. Dunn, J. Zhang, and M.A. Ritenour. 2019. Reduction of Escherichia coli, as a surrogate for Salmonella spp., on the surface of grapefruit during various packingline processes. Food Microbiology. 78:188-193.
    • Type: Journal Articles Status: Published Year Published: 2019 Citation: McEgan, R., L.L. Dunn, and M.D. Danyluk. 2019. Survival of Salmonella on lemon and lime slices and subsequent transfer to beverages. Food Protection Trends. 39:154-161.


    Progress 10/01/17 to 09/30/18

    Outputs
    Target Audience:Produce researchers and growers, Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? Salmonella outbreaks have been linked to imported mangoes, which undergo a heat treatment prior to hydrocooling in order to control and prevent importation of the Mediterranean fruit fly. The purpose of this study is to quantify internalization of Salmonella into different mango varieties. To mimic commercial fruit fly heat treatments, three mango varieties, Ataulfo, Kent, and Tommy Atkins underwent a 75-100 min heat treatment prior to submersion hydrocooling for 30, 40, or 50 min in 21° C water containing a 6.0 log CFU/ml Salmonella cocktail. Alternatively mimicking alternate commercial fruit fly treatments, mangoes rested for 30 min at room temperature following heat treatment and before hydrocooling. Infiltration was determined by sampling flesh from the stem end, middle equatorial section, and blossom end. Internalized Salmonella populations were determined by plating onto Rifampicin supplemented tryptic soy agar in triplicate (n=3). Salmonella infiltration was significantly (P ≤ 0.05) impacted by variety, fruit region, hydrocool time, and addition of rest period between heating and hyrdocooling. Mangoes hyrdrocooled for 50 and 40 min resulted in greater infiltration (3.2 and 3.1 log CFU/segment) compared to 30 min (2.7 log CFU/segment). Tommy Atkins and Atualfo varieties (3.1 and 3.2 log CFU/segment, respectively) were more susceptible to infiltration than Kent with 2.7 log CFU/segment. Greater concentrations of Salmonella were present in flesh sampled from the stem ends for all three varieties (4.0 - 4.7 log CFU/segment) than from the blossom or middle sections (1.9-2.8 log CFU/segment). Finally, the addition of a 30 minute rest period resulted in a significant reduction of internalized Salmonella from 3.1 to 2.8 log CFU/sample (P < 0.05) across all varieties and flesh regions. Salmonella internalizes into whole mangoes with some varieties and regions having greater susceptibility. The addition of a rest period significantly reduces Salmonella infiltration. Survival information for Listeria monocytogenes on food contact surfaces during field packing operations is lacking. Five food contact surfaces (cotton, nitrile, rubber gloves, cotton rags, and stainless steel) were evaluated for pathogen survival. Coupons were autoclaved (clean) or rubbed with a cantaloupe leaf for 20s (fouled), and inoculated with a five-strain cocktail of L. monocytogenes (6 log CFU/ml or g). A wet inoculum was spot inoculated (100µl) onto coupons and dried for 1h. A dry inoculum was prepared by mixing aqueous inoculum with sterile sand and drying for 24h at 40°C, then mixing coupon with 100g of sand for two min. Coupons were held at 35°C (34% RH) for 8h. Samples were stomached for 2 min with 0.1% peptone (100ml), except stainless steel, where a rub-shake-rub was used, and plated onto selective and non-selective media in triplicate experiments with duplicate replicates (n=6). Population decreases following the wet inoculation during drying varied depending on material and cleanliness (i.e. clean nitrile gloves 3.41 log reduction, fouled cotton gloves 0.31 log reduction). Population declines for wet inoculum inoculated surfaces, regardless of fouled or clean , exceeded 1 log except for cotton rags (0.21 log reduction) and gloves (0.92 log reduction). Populations did not decline as rapidly following dry inoculations, but had lower starting populations than wet, but not rapid declines during drying. The trend for dry inoculum are similar regardless of clean or fouled (i.e. stainless steel, 1.34 and 1.33 log reduction for clean and fouled respectively). Population reductions following dry Inoculation were much lower than those following wet inoculation over 8 h (i.e. clean rubber gloves: 4.15 and 0.50 log reduction; and fouled cotton gloves: 1.61 and 0.22 log reduction for wet and dry inoculation, respectively. Inoculation and surface cleanliness method impacts survival of L. monocytogenes on field pack surfaces. Poultry houses in the United States produce 10.2 million tons of litter each year. This high nitrogen containing by-product is frequently applied to agricultural lands as an alternative to synthetic fertilizers but little is known about the prevalence, concentration, or survival of Salmonella in poultry manure used as a soil amendment. This study determined Salmonella concentration and prevalence in raw (untreated) poultry litter from farms in the southern United States in order to inform future regulatory efforts on establishing application-to-harvest interval(s) when amending soils with raw poultry manure to grow produce covered under the FDA's Produce Safety Rule. Poultry litter was collected from 12 broiler and breeder farms in the US states of Florida (1 farm), Georgia (2), Alabama (8), and Texas (1). Seven samples (30 g each) from three to four litter piles at every farm were collected from poultry houses or dry stack sheds. Samples (30 g) were selectively enriched (Rappaport-Vassiliadis [RV] and Tetrathionate [TT] broths) and screened for Salmonella presence by streaking onto Xylose-Lysine-Tergitol 4 agar (XLT4). All presumptive colonies were PCR confirmed as Salmonella. The concentration of Salmonella was determined through concurrent enrichment and serial dilution in MPN reservoirs at the time of screening, which was paused using refrigeration, until Salmonella screening was complete. When a sample was confirmed positive for Salmonella processing of the RV and TT broth MPN reservoirs resumed. Following enrichment, 10 µL from each MPN reservoir was streaked onto XLT4; all presumptive positive Salmonella colonies are PCR confirmed and MPNs calculated. Of the 37 piles sampled from 12 farms, 13 piles (35%) from 6 farms (50%) were positive for Salmonella. Within positive piles, the number of positive samples ranged from 1 to 7 out of 7 collected. The minimum and maximum MPN/g were 1.6 and >280,000, respectively; mean and median MPN/g Salmonella for positive samples were 101,331.6 and 2,850.0, respectively. Salmonella was present on half the farms sampled, in less than half of poultry litter samples collected. Concentrations were highly variable. Contaminated, untreated, poultry litter may pose a health risk if untreated poultry manure contacts produce and the application-to-harvest interval is insufficient to allow for adequate pathogen die-off.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2018 Citation: ., C.A. Baker, M.D. Danyluk, P.Belanger, F. Boelaert, P. Cressey, M. Gheorghe, B. Polkinghorne, H. Toyofuku, and A.H. Havelaar. 2018. Hazard identification of biological hazards in global produce chains. Journal of Food Protection. 81:1171-1186.


    Progress 10/01/16 to 09/30/17

    Outputs
    Target Audience:Produce researchers and growers, Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? This research was initiated to determine the suitability of nonpathogenic E.coli as a surrogate for Salmonella during citrus washing, and to evaluate the removal of E.coli from grapefruit on two pilot packinglines. Whole grapefruit were inoculated with either E. coli or Salmonella onto the equator and dried. Treatments including Fruit wetting (water and 200ppm free chlorine), fruit washing (water, 85ppm peracetic acid (PAA), PAA with an acidic detergent, an alkaline detergent (AD), and an AD with 2% sodium-o-phenylphenate (SOPP)) were applied using a lab scale brush wash system. Individual processes evaluated on the pilot packinglines with E. coli only included fruit wetting, brush washing, pre-wax drying, and wax application plus drying. with ADs, sanitizers, and waxes (shellac and carnauba+morpholine) were evaluated. Treated fruit were rubbed by hand with Dey/Engley neutralizing broth and enumerated on selective and non-selective media. Log reductions for E.coli populations ranged from 2.7 to 4.9, and Salmonella reductions ranged from 2.8 to 4.9. In all lab scale brush wash systems treatments, bacterial population reductions between E.coli and Salmonella were not significantly different (P≤0.05). On pilot packinglines, E. coli populations were reduced by various fruit wetting, washing, waxing, drying and the complete packingline processing treatments by 2.1 to >4.5 log CFU/grapefruit at one packingline system, and by 3.2 to >5.0 log CFU/grapefruit at the other. Treatment of fruit through complete packingline processing at both locations reduced E. coli populations to levels below the detection limit (<1 log CFU/grapefruit). E.coli is an appropriate surrogate for Salmonella under tested conditions; citrus packers can use commercial washing as a Corrective Measure if low microbial quality water was used. The purpose of this research is to evaluate the persistence of foodborne pathogens on the intact surface of whole Ataulfo, Kent, and Tommy Atkins mangoes stored at three different temperaturesOne hundred microliters of a five-strain rifampicin resistant Salmonella spp. or Listeria monocytogenes cocktail (6 log CFU/mango) was spot inoculated onto the mid-section of whole fruit and dried for 1 h. Fruit were stored at 12, 20 or 30 ± 2°C and sampled for up to 28 days. At each sampling point a mango was placed in a sterile bag with 10 ml of 0.1% peptone and bacterial populations were removed by a rub-shake-rub method. Pathogen populations were enumerated by plating onto selective and non-selective media supplemented with rifampicin. Experiments were replicated in duplicate three times for each variety (n=6). Populations of Salmonella increased over storage duration on the surfaces of Kent (0.3 log - 1.1 log CFU/mango) and Tommy Atkins (0.2 - 1.4 log CFU/mango) mangoes at all temperatures. Salmonella populations on Ataulfo mangoes decreased at 12°C (1.6 log CFU/mango) and 30°C (0.4 log CFU/mango) but increased at 20°C (0.1 log CFU/mango). Listeria populations on the surface of Tommy Atkin mangoes increased at all temperatures ranging from 0.1 - 1.4 log CFU/mango. These results imply that postharvest storage of mangoes will not result in sufficient microbial reductions to be used as corrective measures if agriclutural water used during production does not meet the required standards of Produce Safety Rule. The purpose of this study is to evaluate the efficacy of free chlorine and peroxyacetic acid (PAA) to reduce Salmonella populations on the surface of mangoes during brush washing. Whole 'Tommy Atkins' mangoes were spotting inoculated with a 5-strain Salmonella (rifampicin-resistant) cocktail (7 log CFU/mango) onto the equator and dried for 1 h. Mangoes were washed with a pilot brush roller system with either ground water (control), or sanitizer (100 ppm free chlorine (pH=X), or 80 ppm PAA) for 0, 5, 15, 30 and 60 s respectively (n=15 mangoes). Dey/Engley buffer (100 ml) was added to whole mangoes in sterile bags to remove Salmonella from the surface using a rub-shake-rub method, then plated in duplicate onto tryptic soy agar (TSA) and bismuth sulfite agar (BSA) supplemented with rifampicin. Data were statistically analyzed by ANOVA and Tukey's HSD test for effect of sanitizer and time. There were statistically significant differences (P<0.05) in Salmonella reductions between water, chlorine, and PAA treatment regardless of washing time. The highest log reduction with PAA treatment was at 60 s (5.1±1.1), compared with chlorine (4.3±0.8) and water treatment (4.3 0.8). In all cases, log reductions increased with longer treatment times. Chlorine and PAA wash achieved at least 3-log and 4-log CFU/mango reduction, respectively, while water wash alone achieved a 2-log reduction. Addition of free chlorine or PAA to spray water used during brush washing can lead to more effective food safety management, which will help to minimize contaminated mangoes entering the market Avocados were inoculated on the smooth middle section with a 5-strain cocktail (8-log CFU/avocado) of rifampicin resistant Salmonella, dried for 1 h, and submitted to spray washing for 0, 5, 15, 30, and 60 s, using 100 ppm NaOCl (pH 6.5) or 85 ppm PAA, and a water control. Salmonella populations were enumerated following removal from avocadoes using a rub-shake-rub in Dey/Engley (DE) neutralizing broth and spreading dilutions on triptic soy agar (TSA) and bismuth sulfite agar (BSA) supplemented with rifampicin. Experiments of triplicate samples were repeated five times (n+15). Average log CFU/avocado reduction of Salmonella were calculated for each spray time and sanitizer, and compared using Analysis of Variance (ANOVA) and Tukey's HSD (p≤0.05) for each medium.Salmonella populations were reduced significantly more (P≤0.05) by the presence of NaOCl and PAA compared to the water control, for all treatment times on both media types; there were not significantly differences (P>0.05)in Salmonella population reductions between NaOCl and PAA treatments across all treatment times. Salmonella populations were reduced by >3.93 log CFU/avocado with NaOCl and PAA treated for 15 s versus 2.24-log CFU/avocado reduction achieved with water.Addition of NaOCl or PAA can significantly reduce Salmonella populations on the surface of green skin avocados compared to water alone, and may be used as a reduction strategy to prevent or minimize avocado contamination during postharvest practices in Florida packinghouses. The purpose of this study was evaluate the microbial quality of South Florida surface waters. Water samples (1 L) were collected monthly for twelve months at eight study sites along canals in South Florida. Samples were analyzed for turbidity, air temperature, water temperature, pH, and oxidation-reduction potential. Precipitation and relative humidity data were collected from the closest Florida Automated Weather Network location. Samples were enumerated for total aerobic plate count . Total coliforms; generic Escherichia coli were enumerated by calculating the MPN. Samples (100 ml) were evaluated for presence of Salmonella, by enrichment. Presumptive Salmonella colonies were confirmed by invA PCR and serotyped. Salmonella was isolated from 26% of 100 ml samples (25/96). Salmonella concentrations ranged from 0.5 to 3.0 log MPN/100 ml. Coliform populations ranged from 2.6 to 5.2 log MPN/100 ml. Aerobic plate counts were 3.8 to 6.1 log CFU/100 ml. Salmonella detection was not associated with E. coli or coliform populations or chemical or physical water characteristics. Geometric means of E. coli at each site ranged from 0.88 to 1.82 log MPN E. coli/100 ml and statistical threshold values ranged from 1.59 to 2.47 log MPN E. coli/100 ml. Salmonella populations are present in South Florida surface waters and cannot be predicted by total coliforms, generic E. coli or chemical and physical water characteristics.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Havelaar, A.H, K. Vazquez, Z. Topalcengiz, R. Munoz-Carpena, and M.D. Danyluk. 2017. Evaluating the U.S. FSMA Product Safety Rule standard for microbial quality of agricultural water for produce growing. Journal of Food Protection. Journal of Food Protection. 80:2832-1841.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Lambertini, E., J. Barouei, D.W. Schaffner, M.D. Danyluk, and L.J. Harris. 2017. Modeling the risk of salmonellosis from consumption of pistachios produced and consumed in the United States. Food Microbiology. 67:85-96.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Rheault, J-G.E., J. Jeukens. L. Freschi, I. Kukavica-Ibrulj, B. Boyle, M-J. Dupont, A. Colavecchio, V. Barrere, B. Cadieux, M. Kerhoas, A. Crouse, L. Zhu, L. Larivi�re, A.V. Pilar, C. Cavestri, T.K. Chapin, D. Tremblay, C. Vincent, E. Fournier, K. Youfsi, I. Ngueng-Feze, L. Song, V. Usongo, F. Doualla-Bell, C. Berry, A.R. Reimer, N. Kong, C.B. Huang, K. Fong, E.D. Wilson, K. Mukhopadhyay, W. Mottawea, D. Ogunremi, H. Huang, G. Arya, A. Perets, C. Yoshida, J. Robertson, J. Weadge, M.D. Danyluk, J. Rohde, R. Garduno, S. Wang, C. Nadon, P. Thomassin,Y. Joly, I. Fliss, G. Lapointe, L.J. Harris, R. Stephan, E. Burnett, S. Moineau, S. Tamber, S. Bekal, F. Daigle, S. Gruenheid, D. Malo, T. Wittum, P. Delaquis, A. Gill, K.E. Sanderson, M. Wiedmann, E. Franz, L. Wijnands, B.C. Weimer, L.D. Goodridge and R.C. Levesque. 2017. A Syst-OMICS Approach to Ensuring Food Safety and Reducing the Economic Burden of Salmonellosis. Frontiers in Microbiology. 8:996. Doi: 10.3389/fmicb.2017.00996
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Jung, J., L.M. Friedrich, M.D. Danyluk and D.W. Schaffner. 2017. Quantification of transfer of Salmonella from oranges to peel, edible portion, and gloved hands during peeling. Journal of Food Protection. 80:933-939
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Topalcentiz, Z., L.K. Strawn, and M.D. Danyluk. 2017. Microbial quality of agricultural water in Central Florida. PLoS One. 12(4): e0174889. https://doi.org/10.1371/journal.pone.0174889
    • Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Jensen, D.A., M.D. Danyluk, L.J. Harris, and D.W. Schaffner. 2017. Quantifying bacterial cross contamination rates between fresh-cut produce and hands. Journal of Food Protection. 80:213-219.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Schneider, K.R., J. De, Y. Li, A. Sreedharan, R. Goodrich Schneider, M.D. Danyluk, D. Phal, C. Walsh, J. Todd-Searle, D.W. Schaffner, W. Kline, and R.L. Buchanan. 2017. Microbial evaluation of pre- and post-processed tomatoes from Florida, New Jersey, and Maryland Packinghouses. Food Control. 73:511-517.
    • Type: Journal Articles Status: Published Year Published: 2017 Citation: Topalcentiz, Z., and M.D. Danyluk. 2017. Thermal inactivation responses of acid adapted and non-adapted stationary phase Shiga toxin-producing Escherichia coli (STEC), Salmonella spp. and Listeria monocytogenes in orange juice. Food Control. 72:73-82.


    Progress 10/01/15 to 09/30/16

    Outputs
    Target Audience:Produce researchers and growers, Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? The purpose of this study is to compare the survival of Shiga-toxigenic Escherichia coli (STEC), Salmonella, total aerobic count (APC), and generic E. coli in cattle and different wild animal feces found in Florida. Rifampicin resistant 5-strain cocktails STEC and Salmonella were inoculated into domestic cattle and wild animal feces (105 to 106 CFU/g) including deer, wild pig, raccoon, and waterfowl. Fecal samples (1g) were put into 15 ml conical centrifuge tubes for each time interval and stored at room temperature. Populations were enumerated on Day 0, 1, 3, 5, 7, 14, 28 and every 28 days for up to 1 year by addition of 9 ml 0.1% peptone water and spread plating onto TSAR. If no colonies were detected, samples were enriched. A control set of samples were enumerated on TSA and CHROMagar ECC to monitor APC and generic E. coli concentration, respectively. Models for comparison of STEC, Salmonella vs. generic E. coli were developed. Over the 364 day storage, STEC and Salmonella populations declined by 2.4 and 0.8 Log CFU/g in the cattle and 2.1 and 1.6 in the deer feces, respectively. Both Salmonella and STEC behaved the same as in pig, waterfowl, and raccoon samples starting at Day 112 and Day 84, respectively (P<0.05). Salmonella population stayed ≤2.6 log CFU/g after Day 28, and STEC population were ≤2.0 Log CFU/g after Day 14. The rate of generic E. coli decline corresponded to pathogen decline in all fecal types. The calculated predictive power of the models relating pathogen declines to generic E. coli in each fecal type ranged from 0.4362 to 0.9774. Determining appropriate risk mitigation strategies following animal intrusion can improved with a better understanding of pathogen survival in animal feces. The aim of this study was to determine the microbial dispersal due to bird droppings on tomato plants in the field. Four experimental tomato fields, planted and maintained at typical commercial standards, were visited at least twice while fruit were mature (10 visits), and surveyed for contamination with bird droppings. Mature fruit with visible bird droppings, fruit not visually contaminated but within 30 cm of the contamination, fruit on the same plant but more than 30 cm from the contamination, and fruit on the adjacent plants were evaluated for aerobic plate count (APC), coliforms, generic E. coli, and Salmonella. Control fruit were collected from a plant ca. 10 feet away that had no visible bird droppings. Significant differences were determined using the Student's t-Test with Bonferroni correction. Salmonella was isolated from 1/356 samples, collected from fruit on a plant adjacent to a plant contaminated with bird droppings. Populations of coliforms (ca.1.2 log MPN/g) were not significantly different between contaminated and control fruit (p=0.26). APC and generic E. coli ere higher (p=0.006 and p=0.004, respectively) on contaminated fruit (=5.4 log CFU/g, σ=0.6; =0.2 log MPN/g, σ=0.9, respectively) than control fruit (=5.0 log CFU/g, σ=0.6; =-2.0 log MPN/g, σ=0.1, respectively). APC and generic E. coli on tomatoes within 30 cm of contaminated fruit were not significantly different than the controls (=4.8 log CFU/g, σ=0.7; =-1.9 log MPN/g, σ=0.2, respectively). Prevalence of Salmonella on Florida tomatoes was <1%. Enumeration of samples for APC and generic E. coli suggest that microbial populations are not dispersed in high numbers by bird droppings beyond visually contaminated tomatoes. The purpose of this study is to determine populations of indicator organisms and the presence of Salmonella and Shiga Toxin producing Escherichia coli (STEC) genes in agricultural water. Water samples (500 ml) from six agricultural ponds were collected during the 2012/2013 and 2013/2014 growing seasons (46 and 44 samples respectively, 540 total). Microbial indicator populations (total coliforms, generic Escherichia coli, and Enterococci) were enumerated. A microbial water quality profile (WQP) was established for all ponds. Water (150 ml) was filtered and filters stored at -20°C until pathogen analysis by PCR. For STEC, filters were enriched in modified buffered peptone water with pyruvate at 35±2°C for 24 h, DNA extracted, and multiplex PCR for detection of six genes (hly, fliC, eaeA, rfbE, stx-I, and stx-II), run. For Salmonella, the presence of the invA gene was evaluated following a subsequent enrichment in Rappaport-Vassiliadis 42±1°C for 48 h and DNA extraction. All ponds met the current FDA WQP recommendations 100.0% of the time. All STEC genes were detected in 2.6% of the samples. Individual STEC genes varied in the number of samples they were detected in: hly-83.3%, fliC-51.8%, eaeA-17.4%, rfbE-17.4%, stx-I-32.6% stx-II-9.4%. The invA gene was detected in 26/540 (4.8 %) samples, in all ponds and both growing seasons. However, 57.7 % (15/26) of the invA positive samples were from ponds 2 and 4, where the WQP was the poorest. Surface waters tested in Central Florida meet the FDA recommendations for microbial water quality, however at least one Salmonella or STEC gene was detected in 91.3% of samples. Understanding the relationships between indicator microorganisms and pathogens presence allows a greater understanding of agricultural water risks. The purpose of this research was to evaluate the risk of salmonellosis associated with the consumption of North American pecans, accounting for factors that become important after pecans reach the sheller, and to assess the impact of different Salmonella log reduction on the risk of pecan associated illnesses. Probability distributions were chosen to describe the chance of pecan contamination and the effects of storage time, temperature, and processing from published and unpublished data. Salmonella prevalence and concentration was obtained from an in house study; a triangular distribution was used to predict Salmonella prevalence on inshell pecans and the concentration of Salmonella ranged from <0.47 to 39 MPN/100 g. Reductions of up to 5 logs during shelling and processing were evaluated for their impact on predicted illnesses. Population reductions at different temperature conditions and consumer handling practices were obtained from published studies or by consultations with pecan industry. A Beta-Possion model for the dose-response relationship for Salmonella was obtained from published literature. The simulation predicted a mean of 12 illnesses per year and a 91.9% probability of >1 case per year from pecan consumption when no log reductions were assumed during shelling or processing. Hypothetical minimum 3, 4 or 5 log reductions during conditioning, processing or during a combination of both treatments reduced the predicted yearly risk of salmonellosis to 0.8% probability of >1 case per year, and 0.001 and 0.0001 cases of illness per year, respectively. These results suggest that the risk of one or more US cases of salmonellosis per year from consumption of pecans can be reduced from 91.9% to less than 1% by using a process or processes that achieve a minimum 3-log reduction of Salmonella.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2016 Citation: de Moraes, M.H., T.K. Chapin, A. Ginn, A.C. Wright, K. Parker, C. Hoffman, D.W. Pascual, M.D. Danyluk, and M. Teplitski. 2016. Development of an avirulent Salmonella surrogate for modeling pathogen behavior in crop production environments. Applied and Environmental Microbiology. 82:4100-4111
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Turner, A.N., L.M. Friedrich, and M.D. Danyluk. 2016. Influence of temperature differential between tomatoes and postharvest water on Salmonella internalization. Journal of Food Protection. Journal of Food Protection. 79:922-928
    • Type: Journal Articles Status: Published Year Published: 2016 Citation: Brar, P.K., L.K. Strawn, and M.D. Danyluk. 2016. Prevalence, concentration, and types of Salmonella isolated from North American inshell pecans over four harvest years. Journal of Food Protection. 79:352-360.


    Progress 05/04/15 to 09/30/15

    Outputs
    Target Audience:Produce researchers and growers, Extension Agents, Extension Specialists, Researchers State/federal agencies, Government officials, Producers, Processors, Packers, Consultants, Buyers Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?One-on-one activities on farms and packinghouse to offer advice and suggestions on food safety practices. Group Learning workshops to convey materials to stakeholders, including target audiences. In-service trainings to train other educators and future trainers Educational Presentations at scientific and stakeholder conferences Publication of Factsheets, conference proceedings, and non-refereed trade journals. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

    Impacts
    What was accomplished under these goals? Our objective was to evaluate the suitability of Enterococcus faecium (ATCC 8459) as a surrogate of Salmonella during hot water conditioning validation studies of pecans. In-shell pecans (Southern Improved) were inoculated to ca. 7 log CFU/g after drying to the original moisture content and water activity, with either a 5 strain Salmonella cocktail or E. faecium. The cocktail of Salmonella included serotypes Enteritidis PT 30, Enteritidis PT 9c, Oranienburg, Seftenberg and Tennessee. In-shell pecans (50 g) were submerged in a water bath (n=6) at 75±1 (20, 40, 80, 120 s), 80±1 (20, 40, 80, 120 s), 85±1 (20 40, 80, 120 s), 90±1 (20, 40, 60, 80 s) and 95±1°C (20, 40, 60, 80 s). Treated nuts were added to 100 ml of cold TSB, cracked with a hammer and stomached for 1 min. Populations were enumerated onto selective and non-selective media supplemented with nalidixic acid (50 µg/ml). Under all treatment conditions log reductions (Log N/No) of E. faecium were either not significantly different from (P > 0.05), or significantly lower than (P < 0.05), Salmonella. A maximum of 4.8 log reduction was observed following exposure to 95±1°C water for 80 s. Reduction data did not fit into a linear or Weibull model. E. faecium can be successfully used by pecan industry to validate hot water conditioning treatments. As no model to predict reductions during conditioning was developed, the pecan industry should validate individual protocols for achieved log reductions. The aim of this study was to compare survival of Salmonella mutant strains to wild types in soil, water, and on lettuce leaves. Eight Salmonella Typhimurium strains (derived from ATCC 14028), including: a series of five Salmonella Pathogenicity Island (SPI) mutants, from SPI-1 to SPI 5; one strain which contains the entire series of SPI 1-5 mutations (potential avirulent surrogate); and two wild type strains, were evaluated for survivability. The eight strains were individually inoculated at ca. 7 log CFU into i) 250 g freshly collected soil samples; ii) 250 ml sterile EPA "worst-case" water samples; and iii) onto the mid-rib of fresh-cut romaine lettuce leaves. Soil and water samples were incubated at 25° C; lettuce samples were incubated at 4 and 10°C (n=6). Salmonella populations were enumerated at 0, 1, 2, 5, 7, 14, and 21 days or 0, 1, 2, 5, and 7 days for lettuce at 10°C. Significant differences were determined using the Tukey-Kramer test. All Salmonella mutant strains declined significantly (ca. 1 to 4 log CFU/g reduction) in soil over 21 days (P < 0.05). Salmonella populations in soil at day 5 and 21 were significantly lower for the potential surrogate strain containing five SPI mutations than the two wild type strains. Salmonella populations in water and on lettuce leaves remained steady for most strains (ca. 6 log CFU/ml or leaf), including the wild type strains and the potential surrogate strain containing five SPI mutations. The strain of Salmonella with attenuated virulence (five SPI mutations) may be useful as a surrogate in future pilot plant production environment studies. The purpose of this study is to determine populations of indicator organisms and the presence of Salmonella and Shiga Toxin producing Escherichia coli (STEC) genes in agricultural water. Water samples (500 ml) from six agricultural ponds were collected during the 2012/2013 and 2013/2014 growing seasons (46 and 44 samples respectively, 540 total). Microbial indicator populations (total coliforms, generic Escherichia coli, and Enterococci) were enumerated. A microbial water quality profile (WQP) was established for all ponds. Water (150 ml) was filtered and filters stored at -20°C until pathogen analysis by PCR. For STEC, filters were enriched in modified buffered peptone water with pyruvate at 35±2°C for 24 h, DNA extracted, and multiplex PCR for detection of six genes (hly, fliC, eaeA, rfbE, stx-I, and stx-II), run. For Salmonella, the presence of the invA gene was evaluated following a subsequent enrichment in Rappaport-Vassiliadis 42±1°C for 48 h and DNA extraction. All ponds met the current FDA WQP recommendations 100.0% of the time. All STEC genes were detected in 2.6% of the samples. Individual STEC genes varied in the number of samples they were detected in: hly-83.3%, fliC-51.8%, eaeA-17.4%, rfbE-17.4%, stx-I-32.6% stx-II-9.4%. The invA gene was detected in 26/540 (4.8 %) samples, in all ponds and both growing seasons. However, 57.7 % (15/26) of the invA positive samples were from ponds 2 and 4, where the WQP was the poorest. Surface waters tested in Central Florida meet the FDA recommendations for microbial water quality, however at least one Salmonella or STEC gene was detected in 91.3% of samples. Understanding the relationships between indicator microorganisms and pathogens presence allows a greater understanding of agricultural water risks. The objective of this research was to quantify the fate of Escherichia coli O157:H7, Salmonella and Listeria monocytogenes on the surface of whole cantaloupes and watermelons. Rifampicin resistant Escherichia coli O157:H7, Salmonella, or L. monocytogenes (ca. 103 CFU/3.1cm2) cocktails were spot inoculated on the sun-side of whole Athena cantaloupe or watermelons and allowed to dry for 1 hour (n=6). Melons were stored at 4, 10, 15, 20, or 25°C, and sampled up to 21 days. At each time point, the inoculated area (3.1cm2) was excised, stomached with 10 ml of buffer, and pathogen populations were enumerated on both selective and nonselective media supplemented with rifampicin. Salmonella on both melon surfaces, and Escherichia coli O157:H7 on watermelon, declined under all experimental conditions. Escherichia coli O157:H7 on cantaloupe held at 4 and 10°C decreased, but populations increased at 15, 20, and 25°C storage; maximum growth occurred when cantaloupe was stored at 25°C for 3 days (4.9 log CFU/3.1cm2). L. monocytogenes declined on watermelon at 4, 10 and 15°C, but grew on watermelon when held at 20 and 25°C, reaching maximum populations at 7 days of storage (4.2 and 4.5 log CFU/3.1cm2, respectively). L. monocytogenes inoculated onto cantaloupe increased regardless of storage temperature; increases ranged from 0.4 (4°C) to 2.2 (25°C) log CFU/3.1cm2. Maximum populations occurred at 25°C at 7 days of storage (5.3 log CFU/3.1cm2). Food safety risks associated with contamination of whole melons vary depending on pathogen, melon, and postharvest handling. Salmonella did not increase on either watermelon or cantaloupe; E. coli O157:H7 did not increase on watermelon, but did increase above 15°C on cantaloupe; L. monocytogenes increased on watermelon above 20°C and at all temperatures on cantaloupe.

    Publications

    • Type: Journal Articles Status: Published Year Published: 2015 Citation: Luo, Z.Y., G.Y. Gu, A. Ginn, M.C. Giurcanu, P. Adams, G. Vellidis, A.H.C van Bruggen, M.D. Danyluk, A.C. Wright. 2015. Distribution and characterization of Salmonella enterica isolates from irrigation ponds in the Southeastern United States. Applied and Environmental Microbiology. 81: 4376-7387.
    • Type: Journal Articles Status: Published Year Published: 2015 Citation: Jensen, D.A., M.D. Danyluk, L.J. Harris, and D.W. Schaffner. 2015. Quantifying the effect of handwash duration, soap use and drying methods on the removal of Enterobacter aerogenes on hands. Journal of Food Protection,78:685-690.
    • Type: Journal Articles Status: Published Year Published: 2015 Citation: Brar, P.K., L.G. Proano, L.M. Friedrich, L.J. Harris and M.D. Danyluk. 2015. Survival of Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes on raw peanut and pecan kernels stored at -24, 4, and 22�C. Journal of Food Protection, 78:323-332.
    • Type: Journal Articles Status: Published Year Published: 2015 Citation: McEgan, R., and M.D. Danyluk. 2015. Evaluation of aqueous and alcohol-based quaternary ammonium sanitizers for inactivating Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes on peanut and pistachio shells. Food Microbiology, 47:93-98.
    • Type: Journal Articles Status: Published Year Published: 2015 Citation: Jensen, D.A., L.M. Friedrich, L.J. Harris, M.D. Danyluk, and D.W. Schaffner. 2015. Cross-contamination of Escherichia coli O157:H7 between lettuce and wash water during home-scale washing. Food Microbiology, 46:428-433.
    • Type: Journal Articles Status: Published Year Published: 2015 Citation: Liberman, V.M., I.Y. Zhao, D.W. Schaffner, M.D. Danyluk, and L.J. Harris. 2015. Survival or growth of inoculated Escherichia coli O157:H7 and Salmonella on yellow onions (Allium cepa) under conditions simulating food service and consumer handling and storage. Journal of Food Protection, 78:42-50.