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Kristen E. Gibson
Department of Food Science, Division of Agriculture, University of Arkansas, Fayetteville, AR 72704

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Journal article
Published: 28 May 2021 in Applied and Environmental Microbiology
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The microbial quality of agricultural water for fresh produce production is determined by the presence of fecal indicator bacteria (FIB) Escherichia coli despite poor correlations with pathogen presence. Additional FIB such as enterococci have been utilized for assessing water quality. The study objective was to determine the survival times (first time to detect zero or censored) of FIB ( E. coli , enterococci), surrogates ( Listeria innocua, L. seeligeri, Salmonella Typhimurium, PRD1), and pathogens (four strains each of pathogenic E. coli and L. monocytogenes ; five Salmonella serovars) simultaneously inoculated in freshwater mesocosms exposed to diel and seasonal variations. Six separate mesocosm experiments were conducted for ≤ 28 days each season with samples (sediment/water) collected each day for the first seven days and weekly thereafter. Microorganisms survived significantly longer in sediment compared to those in water [Hazard ratio (HR) for water/sediment is 2.2 (95%CI: 1.79, 2.71)]. Also, FIB E. coli survived significantly longer than FIB enterococci [HR for enterococci/ E.coli is 12.9 (95%CI: 8.18, 20.37)] after adjusting for the sediment/water and lake/river effects. Differences in the area under the curve (calculated from log CFU or PFU over time) were used to assess pathogen and surrogate survival in relation to FIB. Despite sample type (sediment/water) and seasonal influences, pathogenic Salmonella spp. survived similar to FIB E. coli , and L. monocytogenes and pathogenic E. coli survived similar to FIB enterococci. Further investigation of microbial survival in water and sediment is needed to determine which surrogates are best suited to assess pathogen survival in agricultural water used in in irrigation water for fresh produce. IMPORTANCE Contamination of fresh produce via agricultural water is well established. This research demonstrates that survival of fecal indicator bacteria, pathogenic microorganisms, and other bacterial and viral surrogates in freshwater differs by sample type (sediment/water) and season. Our work highlights potential risks associated with pathogen accumulation and survival in sediment, and the possibility for resuspension and contamination of agricultural water used in fresh produce production. Specifically, a greater microbial persistence in sediments versus water over time was observed, along with differences in survival among microorganisms in relation to fecal indicator bacteria E. coli and enterococci. Previous studies compared data among microbial groups in different environments. Conversely, fecal indicator bacteria, surrogates, and pathogenic microorganisms were assessed within the same water and sediment mesocosms in the present study during four seasons, better representing the agricultural aquatic environment. This data should be considered when determining agricultural microbial water quality criteria in fresh produce operations.

ACS Style

Christopher A. Baker; Giselle Almeida; Jungae Lee; Kristen E. Gibson. Pathogen and Surrogate Survival in Relation to Fecal Indicator Bacteria in Freshwater Mesocosms. Applied and Environmental Microbiology 2021, 1 .

AMA Style

Christopher A. Baker, Giselle Almeida, Jungae Lee, Kristen E. Gibson. Pathogen and Surrogate Survival in Relation to Fecal Indicator Bacteria in Freshwater Mesocosms. Applied and Environmental Microbiology. 2021; ():1.

Chicago/Turabian Style

Christopher A. Baker; Giselle Almeida; Jungae Lee; Kristen E. Gibson. 2021. "Pathogen and Surrogate Survival in Relation to Fecal Indicator Bacteria in Freshwater Mesocosms." Applied and Environmental Microbiology , no. : 1.

Original paper
Published: 20 April 2021 in Food and Environmental Virology
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Retail foodservice establishments (FSE) frequently utilize washes with sanitizing agents during fresh produce preparation. This study evaluated the efficacy of ozonated water on the inactivation of viruses, bacteria, and viruses in association with bacteria on produce surfaces. Boston bibb lettuce (BB) and cherry tomatoes were spot inoculated with viruses (murine norovirus (MNV) and MS2 bacteriophage), bacteria (Enterobacter cloacae and Bacillus cereus), or MNV associated with E. cloacae or B. cereus. Following inoculation, produce was held at 4 °C for 90 min (virus, virus + bacteria) or 24 h (virus, bacteria) prior to treatment. A batch wash ozone sanitation system (BWOSS) was prepared with ice (3–5 °C) and 0.5 ppm initial ozone concentration or no ozone. Produce samples were treated for 40 min with an ozonated water (0.86–0.99 ppm) or water-only wash with samples taken every 10 min. Samples were processed for microbial recovery, and plaque forming units (PFU) and colony forming units remaining on the produce were determined. Although microbial reductions of 99 to 99.99% were achieved during ozone treatments, few statistically significant differences (P > 0.1) were detected when comparing the ozonated water to water-only wash. Notably, a significant difference (P = 0.009) in log reduction of MNV + bacteria and MNV alone on BB was observed after 40 min ozonated water wash. Specifically, MNV with B. cereus achieved a 1−log greater reduction (2.60 log PFU/ml) compared to MNV alone (1.63 log PFU/ml). Overall, washing produce in ozonated water did not significantly increase microbial inactivation compared to water alone under the conditions presented here. Variables impacting ozone wash effectiveness should be considered when implementing produce wash sanitation systems within FSE.

ACS Style

Cailin R. Dawley; Jung Ae Lee; Kristen E. Gibson. Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone. Food and Environmental Virology 2021, 13, 390 -400.

AMA Style

Cailin R. Dawley, Jung Ae Lee, Kristen E. Gibson. Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone. Food and Environmental Virology. 2021; 13 (3):390-400.

Chicago/Turabian Style

Cailin R. Dawley; Jung Ae Lee; Kristen E. Gibson. 2021. "Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone." Food and Environmental Virology 13, no. 3: 390-400.

Journal article
Published: 20 April 2021 in International Journal of Food Microbiology
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The U.S. FDA Food Safety Modernization Act Preventive Controls for Human Food Rule underlines the importance of an effective environmental monitoring (EM) program. EM is used to determine harborage sites of microorganisms on processing equipment, assess effectiveness of sanitation programs, and prevent transmission of foodborne pathogens. This study characterizes commercially-available polyurethane foam (PUF) and cellulose (CELL) EM tools for their efficacy in the release of foodborne pathogens from their sponge matrices. Specifically, the objectives of this study were to 1) compare the ability of EM tools to release microorganisms into a recovery eluent, 2) characterize EM tool performance at decreasing inoculum concentrations, and 3) assess the impact of various operators during the processing of EM samples. Two bacteria (Listeria monocytogenes, Salmonella Typhimurium) and one human norovirus surrogate (Tulane virus [TV]) were compared at decreasing inoculum levels utilizing two elution techniques (mechanical stomacher, manually by operator), and across six operators. Data indicated that EM tool material composition impacted the release of microorganisms (p = 0.0001), where the PUF EM tool released TV more readily than the CELL EM tool. Conversely, the decreasing inoculum levels did not statistically differ in the release of microorganisms from the EM tool matrices. In addition, no significant difference was found between the machine stomacher and manual elution by human operator or between operators. Overall, the study provides a detailed characterization of two commercially-available EM tools, and the differences identified in this study can be used to improve the effectiveness of EM programs.

ACS Style

Sarah L. Jones; Kristen E. Gibson. Factors impacting microbial release from environmental monitoring tools. International Journal of Food Microbiology 2021, 347, 109198 .

AMA Style

Sarah L. Jones, Kristen E. Gibson. Factors impacting microbial release from environmental monitoring tools. International Journal of Food Microbiology. 2021; 347 ():109198.

Chicago/Turabian Style

Sarah L. Jones; Kristen E. Gibson. 2021. "Factors impacting microbial release from environmental monitoring tools." International Journal of Food Microbiology 347, no. : 109198.

Journal article
Published: 30 November 2020 in Food Control
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Strawberries, the fifth most preferred fresh fruit in the United Sates, are one of several fresh produce commodities in the U.S. linked to outbreaks of foodborne disease. However, the industry is not well characterized. Additionally, in the southeastern U.S. (SEUS), very small strawberry-growing operations are particularly common, presenting unique challenges to implementation of risk management practices (RMP). A 45-item survey was developed to collect data regarding each strawberry grower’s location, farm characteristics, and RMP. The majority of SEUS growers in this study harvested strawberries on less than 5 acres with 2.00-4.99 acres being most common (41%) and reported a revenue based on strawberry production of US$25,001-250,000 (63%). Implementation of a pre-harvest policy and animal intrusion monitoring were both highly prevalent whereas testing of pre-harvest agricultural water was least common. Growers also reported using RMP but were less likely to document them. For example, 76.6% of growers reported their employees had attended food safety training; meanwhile, only 38.9% had documented training. The frequency of use and documentation of RMP were also found to be impacted by certain farm characteristics, most notably acreage, revenue, presence of third-party audit, and presence of a written food safety plan. Based on these results, strawberry growers, particularly in the SEUS, may benefit from additional education tailored to align with farm scale that includes instruction on documentation.

ACS Style

Thomas A. Yeargin; Angela M. Fraser; Kristen E. Gibson. Characterization of risk management practices among strawberry growers in the southeastern United States and the factors associated with implementation. Food Control 2020, 122, 107758 .

AMA Style

Thomas A. Yeargin, Angela M. Fraser, Kristen E. Gibson. Characterization of risk management practices among strawberry growers in the southeastern United States and the factors associated with implementation. Food Control. 2020; 122 ():107758.

Chicago/Turabian Style

Thomas A. Yeargin; Angela M. Fraser; Kristen E. Gibson. 2020. "Characterization of risk management practices among strawberry growers in the southeastern United States and the factors associated with implementation." Food Control 122, no. : 107758.

Review
Published: 24 November 2020 in Agriculture
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Produce-associated foodborne disease outbreaks have increased worldwide highlighting the importance of proper implementation of risk management practices (RMP). We determined the relationship between environmental characteristics (i.e., physical resources) of produce farms and implementation of RMP. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses principles, we identified 36 studies to include in our analysis. Most study data were collected through surveys administered to growers in developed countries. Quality assessment results showed that studies on this topic should be more rigorously conducted (e.g., powering sample sizes and training data collectors) to yield better quality evidence. Agricultural waters were the most common environmental characteristic assessed, with many farms using unsafe water sources. Hygiene aids (e.g., accessible handwashing facilities), were lacking across many farms. Animal intrusion RMP were the least commonly assessed environmental characteristic. Only one study tested the relationship between on-farm environmental characteristics and RMP implementation reporting a positive relationship between accessible handwashing and worker hygiene practices. Grower knowledge and perception of RMP combined with cost and ease in carrying out RMP might influence the availability of physical resources for proper RMP implementation. These results can inform practical interventions aimed to increase adoption of RMP on produce farms.

ACS Style

Dilhani Jayawardhana; Loan Cao; Thomas Yeargin; Kristen Gibson; Angela M. Fraser. The Relationship between Environmental Characteristics and Risk Management Practices on Produce Farms: A Systematic Literature Review. Agriculture 2020, 10, 577 .

AMA Style

Dilhani Jayawardhana, Loan Cao, Thomas Yeargin, Kristen Gibson, Angela M. Fraser. The Relationship between Environmental Characteristics and Risk Management Practices on Produce Farms: A Systematic Literature Review. Agriculture. 2020; 10 (12):577.

Chicago/Turabian Style

Dilhani Jayawardhana; Loan Cao; Thomas Yeargin; Kristen Gibson; Angela M. Fraser. 2020. "The Relationship between Environmental Characteristics and Risk Management Practices on Produce Farms: A Systematic Literature Review." Agriculture 10, no. 12: 577.

Original article
Published: 12 May 2020 in Journal of Applied Microbiology
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Aims This study measured the survival of Listeria monocytogenes and Salmonella enterica subsp. enterica serovar Javiana over a 10-day period on four soil-free cultivation matrix (SFCM) types in the absence of microgreens and fertilizers. Methods and Results Coco coir (CC), a Sphagnum peat/vermiculite mix, Biostrate® and hemp mat samples were inoculated with 3 × 106 CFU per ml bacteria, incubated at room temperature, and analysed on day 0, 1, 3, 6, and 10. Statistically significant differences in pathogen survival were observed across multiple time points for hemp and Biostrate compared to CC, peat and bacteria in phosphate buffered saline (PBS) (P < 0·05). S. Javiana showed greater overall survival compared to Listeria (P < 0·0002). By day 10, S. Javiana persisted at the initial inoculum concentration for hemp and Biostrate while declining by 1–2 log CFU per ml in CC, peat and PBS. Listeria also persisted at the initial concentration in hemp and Biostrate but decreased to 1 log CFU per ml in peat and below the detection limit in CC and PBS. Conclusions Overall, there are survival differences between bacterial pathogens in SFCM used in microgreen production systems. To our knowledge, this is the first comparison of survival among SFCM involving a S. enterica serovar and L. monocytogenes, and the first study comparing CC, Biostrate and hemp. Significance and Impact of the Study Microgreens production systems predominantly utilize soil alternatives, and it is not well-understood how pathogen transmission risk may be affected by the type of SFCM. The results of this study impact the microgreen industry as media selection may be used to reduce the risk of bacterial pathogen proliferation and transmission to the plant potentially resulting in potential foodborne illness.

ACS Style

G. Misra; K.E. Gibson. Survival of Salmonella enterica subsp. enterica serovar Javiana and Listeria monocytogenes is dependent on type of soil‐free microgreen cultivation matrix. Journal of Applied Microbiology 2020, 129, 1720 -1732.

AMA Style

G. Misra, K.E. Gibson. Survival of Salmonella enterica subsp. enterica serovar Javiana and Listeria monocytogenes is dependent on type of soil‐free microgreen cultivation matrix. Journal of Applied Microbiology. 2020; 129 (6):1720-1732.

Chicago/Turabian Style

G. Misra; K.E. Gibson. 2020. "Survival of Salmonella enterica subsp. enterica serovar Javiana and Listeria monocytogenes is dependent on type of soil‐free microgreen cultivation matrix." Journal of Applied Microbiology 129, no. 6: 1720-1732.

Original paper
Published: 21 February 2020 in Food and Environmental Virology
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The U.S. FDA Food Safety Modernization Act Preventive Controls for Human Food Rule emphasizes the importance of an effective environmental monitoring (EM) program. This study aims to characterize polyurethane foam (PUF) EM tools-currently used in the food industry for the recovery of bacteria from food contact surfaces-for their efficacy in the release and recovery of human enteric viruses. Two viruses (human norovirus [hNoV] and Tulane virus [TV]) were compared at varying inoculum levels, with two EM tools (PUF swab and sponge), two delayed processing times (24 h and 72 h), and one surface type (stainless steel [SS]). Specifically, the objectives were to (1) determine the ability of PUF devices to release viruses for detection and (2) assess the ability of PUF devices to recover viruses from SS surfaces. For TV release from the sponge, there was a significant difference (p = 0.0064) when compared across inoculum level (105 plaque forming unit [PFU]/sponge vs. 102 PFU/sponge). Release of hNoV at a single inoculum level by PUF sponge and swab was compared resulting in a significant difference (p < 0.0001). Data on recovery of TV from SS surfaces using both the sponge and swab indicate significant differences depending on the inoculum level. Recovery of hNoV from SS surfaces differed significantly (p = 0.0030) between the sponge and swab devices. Overall, the study provides a detailed characterization of two commercially available, PUF-based EM tools, and the differences identified in this study can be used to improve the efficacy of EM tools.

ACS Style

Sarah Jones; Kristen E. Gibson. Characterization of Polyurethane Foam Environmental Monitoring Tools for the Recovery and Release of Viruses. Food and Environmental Virology 2020, 12, 158 -166.

AMA Style

Sarah Jones, Kristen E. Gibson. Characterization of Polyurethane Foam Environmental Monitoring Tools for the Recovery and Release of Viruses. Food and Environmental Virology. 2020; 12 (2):158-166.

Chicago/Turabian Style

Sarah Jones; Kristen E. Gibson. 2020. "Characterization of Polyurethane Foam Environmental Monitoring Tools for the Recovery and Release of Viruses." Food and Environmental Virology 12, no. 2: 158-166.

Journal article
Published: 21 December 2019 in Foods
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Purchasing fresh and local produce at farmers markets has seen an increasing trend over the past decade. However, with this rise in popularity food safety challenges need to be recognized and addressed. Farmers market managers play a significant role in ensuring that vendors implement food safety practices at the market. Thus, this study investigated the food safety perceptions of farmers markets managers and vendors in Texas and Arkansas. A total of 123 participants were surveyed, including 38 managers and 85 vendors. The survey included a series of questions to determine gaps in vendor and manager food safety knowledge as well as the barriers and factors that prevent the implementation of relevant food safety practices. The results indicate that a lack of facilities, equipment, and resources containing food safety guidelines specific to farmers markets were the major barriers to the implementation of food safety practices. In addition, only 36.7% of participants had formal food safety training (e.g., ServSafe) and approximately 50% of the market managers provided food safety materials to their vendors. Overall, these data suggest that the development of farmers market-specific training programs to enhance food safety behaviors and practices in farmers markets would be beneficial to stakeholders.

ACS Style

Zahra H. Mohammad; Heyao Yu; Jack A. Neal; Kristen E. Gibson; Sujata A. Sirsat. Food Safety Challenges and Barriers in Southern United States Farmers Markets. Foods 2019, 9, 12 .

AMA Style

Zahra H. Mohammad, Heyao Yu, Jack A. Neal, Kristen E. Gibson, Sujata A. Sirsat. Food Safety Challenges and Barriers in Southern United States Farmers Markets. Foods. 2019; 9 (1):12.

Chicago/Turabian Style

Zahra H. Mohammad; Heyao Yu; Jack A. Neal; Kristen E. Gibson; Sujata A. Sirsat. 2019. "Food Safety Challenges and Barriers in Southern United States Farmers Markets." Foods 9, no. 1: 12.

Journal article
Published: 01 July 2019 in Food Control
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An estimated 9.4 million illnesses are due to known foodborne pathogens every year. Consumption of fresh produce can be a risk factor for the transmission of foodborne pathogens with the potential for contamination occurring at any node in the farm to fork food pathway. Retail settings present several opportunities for cross-contamination of fresh produce to occur. Washing with the addition of a sanitizing agent is the primary intervention method or the inactivation of microorganisms potentially present on fresh produce. The present study evaluated the efficacy of a batch wash ozone sanitation system (BWOSS) for the inactivation of microorganisms on the surface of fresh produce. Three microorganisms (Escherichia coli, Listeria innocua, Salmonella Typhimurium), four types of fresh produce (tomatoes, strawberries, cilantro, romaine head lettuce), and three factors (water temperature, free chlorine, organic load) were utilized in a Central Composite Design to characterize the efficacy of the BWOSS. Multiple comparisons among microorganism type indicate significantly greater log reduction (P < 0.05) of L. innocua across all time points (4.7 logs) when compared to E. coli (4.2 logs) when all produce types were combined. Meanwhile, microbial reduction on cilantro by ozone treatment was generally lower than on all other produce types and significantly lower (P < 0.05) than cherry tomatoes at all time points. A principal component (PC) analysis was performed, and PC1 was found to represent the joint effect of water temperature, ozone, and ORP where water temperature was negatively correlated with ozone and accounted for 47% of the total variation of all of the explanatory variables. Combined with water temperature, free chlorine and organic load comprised 91% of the total variation in the BWOSS—indicating the critical nature of these variables in the ability to maintain effective ozone concentrations. Overall, this study provides a detailed analysis of the impact of critical variables on the inactivation efficacy of aqueous ozone within a BWOSS for use in retail food service establishments.

ACS Style

Kristen E. Gibson; Giselle Almeida; Sarah Jones; Kacy Wright; Jung Ae Lee. Inactivation of bacteria on fresh produce by batch wash ozone sanitation. Food Control 2019, 106, 106747 .

AMA Style

Kristen E. Gibson, Giselle Almeida, Sarah Jones, Kacy Wright, Jung Ae Lee. Inactivation of bacteria on fresh produce by batch wash ozone sanitation. Food Control. 2019; 106 ():106747.

Chicago/Turabian Style

Kristen E. Gibson; Giselle Almeida; Sarah Jones; Kacy Wright; Jung Ae Lee. 2019. "Inactivation of bacteria on fresh produce by batch wash ozone sanitation." Food Control 106, no. : 106747.

Original paper
Published: 26 March 2019 in Food and Environmental Virology
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Human noroviruses (hNoV) are the primary cause of foodborne disease in the USA. Most studies on inactivation kinetics of hNoV and its surrogates are performed in monoculture, while the microbial ecosystem effect on virus inactivation remains limited. This study investigated the persistence of hNoV surrogates, murine norovirus (MNV) and Tulane virus (TuV), along with Aichi virus (AiV) under thermal and chemical inactivation in association with Gram-negative (Enterobacter cloacae) bacteria. Thermal inactivation of viruses in co-culture with E. cloacae revealed no protective effects of bacteria. At 56 °C, AiV with and without bacteria was completely inactivated by 10 min with decimal reduction values (D-values) of 41 and 43 s, respectively. Similar results were also observed for TuV. Conversely, MNV with bacteria was completely inactivated by 10 min while MNV alone remained stable up to 30 min at 56 °C. Both MNV and TuV were slightly more stable than AiV at 63 °C with TuV detection up to 2 min without bacteria. For chemical inactivation on stainless steel surfaces, viruses alone and in association with bacteria were treated with 1000 ppm sodium hypochlorite. Virus association with bacteria had no significant effect (p > 0.05) on virus resistance to bleach inactivation compared to virus alone. Specifically, exposure to 1000 ppm bleach for 5 min resulted in an average of 3.86, 2.14, and 0.94 log10 PFU/ml reductions for TuV, MNV, and AiV without bacteria, respectively. Reductions in TuV, MNV, and AiV were 3.50, 1.88, and 0.61 log10 PFU/ml when associated with E. cloacae, respectively.

ACS Style

Wenjun Deng; Giselle Almeida; Kristen E. Gibson. Co-culture with Enterobacter cloacae does not Enhance Virus Resistance to Thermal and Chemical Treatments. Food and Environmental Virology 2019, 11, 238 -246.

AMA Style

Wenjun Deng, Giselle Almeida, Kristen E. Gibson. Co-culture with Enterobacter cloacae does not Enhance Virus Resistance to Thermal and Chemical Treatments. Food and Environmental Virology. 2019; 11 (3):238-246.

Chicago/Turabian Style

Wenjun Deng; Giselle Almeida; Kristen E. Gibson. 2019. "Co-culture with Enterobacter cloacae does not Enhance Virus Resistance to Thermal and Chemical Treatments." Food and Environmental Virology 11, no. 3: 238-246.

Review
Published: 15 March 2019 in Horticulturae
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Controlled environment agriculture (CEA) is a growing industry for the production of leafy vegetables and fresh produce in general. Moreover, CEA is a potentially desirable alternative production system, as well as a risk management solution for the food safety challenges within the fresh produce industry. Here, we will focus on hydroponic leafy vegetable production (including lettuce, spinach, microgreens, and herbs), which can be categorized into six types: (1) nutrient film technique (NFT), (2) deep water raft culture (DWC), (3) flood and drain, (4) continuous drip systems, (5) the wick method, and (6) aeroponics. The first five are the most commonly used in the production of leafy vegetables. Each of these systems may confer different risks and advantages in the production of leafy vegetables. This review aims to (i) address the differences in current hydroponic system designs with respect to human pathogen internalization risk, and (ii) identify the preventive control points for reducing risks related to pathogen contamination in leafy greens and related fresh produce products.

ACS Style

Gina Riggio; Sarah Jones; Kristen Gibson. Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation. Horticulturae 2019, 5, 25 .

AMA Style

Gina Riggio, Sarah Jones, Kristen Gibson. Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation. Horticulturae. 2019; 5 (1):25.

Chicago/Turabian Style

Gina Riggio; Sarah Jones; Kristen Gibson. 2019. "Risk of Human Pathogen Internalization in Leafy Vegetables During Lab-Scale Hydroponic Cultivation." Horticulturae 5, no. 1: 25.

Review
Published: 05 October 2018 in International Journal of Food Microbiology
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The food safety implications of microgreens, an emerging salad crop, have been studied only minimally. The farm to fork continuum of microgreens and sprouts has some overlap in terms of production, physical characteristics, and consumption. This review describes the food safety risk of microgreens as compared to sprouts, potential control points for microgreen production, what is known to date about pathogen transfer in the microgreen production environment, and where microgreens differ from sprouts and their mature vegetable counterparts. The synthesis of published research to date may help to inform Good Agricultural Practices (GAPs) and Good Handling Practices (GHPs) for the emerging microgreen industry.

ACS Style

Gina M. Riggio; Qing Wang; Kalmia E. Kniel; Kristen E. Gibson. Microgreens—A review of food safety considerations along the farm to fork continuum. International Journal of Food Microbiology 2018, 290, 76 -85.

AMA Style

Gina M. Riggio, Qing Wang, Kalmia E. Kniel, Kristen E. Gibson. Microgreens—A review of food safety considerations along the farm to fork continuum. International Journal of Food Microbiology. 2018; 290 ():76-85.

Chicago/Turabian Style

Gina M. Riggio; Qing Wang; Kalmia E. Kniel; Kristen E. Gibson. 2018. "Microgreens—A review of food safety considerations along the farm to fork continuum." International Journal of Food Microbiology 290, no. : 76-85.

Review article
Published: 23 September 2018 in Journal of Applied Microbiology
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Viral enteropathogens are one of the leading causative agents of foodborne illnesses in both the United States and the European Union. While human noroviruses (hNoV) and Hepatitis A virus (HAV) cause the vast majority of outbreaks and illnesses, there are handful of human enteric viruses that contribute to sporadic outbreaks worldwide including astrovirus, sapovirus, rotavirus, enterovirus, and Aichi virus. In addition, Hepatitis E virus is increasingly being recognized as an emerging zoonotic threat within the food supply. This review aims to briefly describe the primary human enteric viruses of concern with respect to foodborne transmission. Next, we focus on the contamination and persistence of these viruses within three high risk food commodities—leafy greens, soft red fruits, and bivalve mollusks. As opposed to detailing the specific routes by which these foods can be contaminated with enteric viruses, we have chosen to focus on their persistence and specific interactions within the food itself. Therefore, the processes of attachment and internalization of the viruses in foods have been emphasized. Looking forward, the implications of these specific interactions of human enteric viruses with leafy greens, soft red fruits, and bivalve mollusks are briefly considered within the context of future prevention and control strategies. This article is protected by copyright. All rights reserved.

ACS Style

Thomas Yeargin; Kristen E Gibson. Key characteristics of foods with an elevated risk for viral enteropathogen contamination. Journal of Applied Microbiology 2018, 126, 996 -1010.

AMA Style

Thomas Yeargin, Kristen E Gibson. Key characteristics of foods with an elevated risk for viral enteropathogen contamination. Journal of Applied Microbiology. 2018; 126 (4):996-1010.

Chicago/Turabian Style

Thomas Yeargin; Kristen E Gibson. 2018. "Key characteristics of foods with an elevated risk for viral enteropathogen contamination." Journal of Applied Microbiology 126, no. 4: 996-1010.

Review
Published: 01 October 2017 in International Journal of Food Microbiology
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Human noroviruses (hNoV) are one of the major causes of foodborne disease outbreaks linked to leafy greens. However, the interactions-including attachment and persistence-of hNoV with leafy greens are not well characterized. In the present review, three mechanisms are hypothesized for the interaction of hNoV with leafy green phyllospheres: 1) specific binding to histo-blood group antigen (HBGA)-like carbohydrates exposed on leaf surfaces and present on bacterial microbiota; 2) non-specific binding through electrostatic forces; and 3) internalization of hNoV through contaminated water (e.g. hydroponic feed water). To add more complexity, there is a rich diversity of microbial communities (i.e., bacteria, fungi, protozoa) residing in leafy green phyllospheres, and the attachment and persistence of hNoV could be largely impacted by these microorganisms through direct and indirect interactions. For instance, enzymes produced by bacteria and fungi could potentially compromise the structure of HBGA-like carbohydrate binding sites on leaves, leading to a reduction in hNoV binding. On the other hand, some bacteria also possess HBGA-like binding sites on their cell surface, which may provide extra binding locations for hNoV. There are also numerous metabolic compounds that can be produced by leafy greens and its microbial inhabitants and be subsequently distributed within leafy green phyllospheres. These compounds could theoretically play roles in enhancement or reduction in the attachment of hNoV. Overall, increasing the understanding of the various types of hNoV attachment and interactions with leafy green phyllospheres will be crucial for elucidating hNoV transmission via leafy greens as well as for the development of effective control measures.

ACS Style

Wenjun Deng; Kristen E. Gibson. Interaction of microorganisms within leafy green phyllospheres: Where do human noroviruses fit in? International Journal of Food Microbiology 2017, 258, 28 -37.

AMA Style

Wenjun Deng, Kristen E. Gibson. Interaction of microorganisms within leafy green phyllospheres: Where do human noroviruses fit in? International Journal of Food Microbiology. 2017; 258 ():28-37.

Chicago/Turabian Style

Wenjun Deng; Kristen E. Gibson. 2017. "Interaction of microorganisms within leafy green phyllospheres: Where do human noroviruses fit in?" International Journal of Food Microbiology 258, no. : 28-37.

Journal article
Published: 01 September 2017 in Journal of Environmental Quality
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Standard methods for the evaluation of recreational water quality rely on generic bacterial indicators such as Escherichia coli. However, E. coli does not provide enough information to determine fecal source or public health risk. The stsudy objective was to determine factors influencing the presence of E. coli and host-specific markers (HSM) from upstream to downstream in Beaver Lake Reservoir (BLR). From February 2014 to September 2015, 420 base flow and rain event samples were collected from seven sites—two sites from streams (White River [WR] and War Eagle Creek) draining into BLR and five sites from within BLR. Each sample was analyzed for E. coli and by quantitative polymerase chain reaction for HSM related to human, bovine, and poultry. The data indicate that overall levels of E. coli were significantly greater in the WR and significantly lower at the most downstream sampling location in BLR. Escherichia coli is more likely present during spring (adjusted odds ratio [aOR] = 1.86), at the WR sampling site (aOR = 3.39), or during a rain event (aOR = 2.73). Moreover, the HSM HumM2 is more likely present (aOR = 1.99) when E. coli is present. These same factors were associated with E. coli concentrations >126 most probable number 100 mL−1 (aOR = 2.76–12.48), except the poultry marker CL was more likely associated (aOR = 3.81) than HumM2. This study revealed that both seasonal and locational factors are important variables for fecal pollution in BLR. Moreover, these same factors may apply to fecal pollution in manmade reservoirs within similar types of watersheds across the United States, as well as internationally. Copyright © 2017. . Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

ACS Style

Kristen E. Gibson; Jung Ae Lee; Jay M. Jackson; Lauren N. Smith; Giselle Almeida. Identification of Factors Affecting Fecal Pollution in Beaver Lake Reservoir. Journal of Environmental Quality 2017, 46, 1048 -1056.

AMA Style

Kristen E. Gibson, Jung Ae Lee, Jay M. Jackson, Lauren N. Smith, Giselle Almeida. Identification of Factors Affecting Fecal Pollution in Beaver Lake Reservoir. Journal of Environmental Quality. 2017; 46 (5):1048-1056.

Chicago/Turabian Style

Kristen E. Gibson; Jung Ae Lee; Jay M. Jackson; Lauren N. Smith; Giselle Almeida. 2017. "Identification of Factors Affecting Fecal Pollution in Beaver Lake Reservoir." Journal of Environmental Quality 46, no. 5: 1048-1056.

Review article
Published: 17 June 2017 in Journal of Virological Methods
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Acute gastroenteritis causes the second highest infectious disease burden worldwide. Human enteric viruses have been identified as leading causative agents of acute gastroenteritis as well as foodborne illnesses in the U.S. and are generally transmitted by fecal-oral contamination. There is growing evidence of transmission occurring via contaminated fomite including food contact surfaces. Additionally, human enteric viruses have been shown to remain infectious on fomites over prolonged periods of time. To better understand viral persistence, there is a need for more studies to investigate this phenomenon. Therefore, optimization of surface sampling methods is essential to aid in understanding environmental contamination to ensure proper preventative measures are being applied. In general, surface sampling studies are limited and highly variable among recovery efficiencies and research parameters used (e.g., virus type/density, surface type, elution buffers, tools). This review aims to discuss the various factors impacting surface sampling of viruses from fomites and to explore how researchers could move towards a more sensitive and standard sampling method.

ACS Style

Nicole L. Turnage; Kristen E. Gibson. Sampling methods for recovery of human enteric viruses from environmental surfaces. Journal of Virological Methods 2017, 248, 31 -38.

AMA Style

Nicole L. Turnage, Kristen E. Gibson. Sampling methods for recovery of human enteric viruses from environmental surfaces. Journal of Virological Methods. 2017; 248 ():31-38.

Chicago/Turabian Style

Nicole L. Turnage; Kristen E. Gibson. 2017. "Sampling methods for recovery of human enteric viruses from environmental surfaces." Journal of Virological Methods 248, no. : 31-38.

Journal article
Published: 31 December 2015 in Current Microbiology
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Staphylococcus aureus is considered an important human pathogen. This study aimed to investigate the combination of essential oil compounds (EOCs) and bacteriophage as alternative antimicrobials to control S. aureus in vitro. Here, four EOCs (alpha-pinene, 3-carene, (+)-limonene, (1S)-(-)-β-pinene) were evaluated by disc diffusion assay (DDA) and growth inhibition assay (GIA) to determine inhibitory effects against five strains of S. aureus. Phage adsorption assays were performed with phage K up to 120 h at 6, 13, and 37 °C to determine lytic activity. Combinations of phage K and EOCs against S. aureus were also evaluated at 37 °C. Alpha-pinene exhibited significantly greater inhibition towards S. aureus strains when compared to other EOCs tested by the DDA. GIAs indicate that all S. aureus strains exhibited significantly reduced growth (P < 0.006) over a 48-h period when exposed to EOCs. Phage adsorption assays indicate that phage K has high lytic activity at 37 °C with at least a 1.5-log increase in the number of plaque-forming units (PFU) over 6 h when compared to 6 and 13 °C. S. aureus strains showed significantly reduced growth (P < 0.05) when treated with combined phage K and EOCs. Results from the combined effect of EOC and phage indicate that phage alone inhibits S. aureus in vitro at 37 °C as effectively as EOCs alone or in combination with phage with variability between strains. The results from DDA, GIA, and phage adsorption assays indicate that select EOCs and phage K can be used as antimicrobials against S. aureus in vitro with potential application in situ.

ACS Style

Anisha Ghosh; Steven C. Ricke; Giselle Almeida; Kristen E. Gibson. Combined Application of Essential Oil Compounds and Bacteriophage to Inhibit Growth of Staphylococcus aureus In Vitro. Current Microbiology 2015, 72, 426 -435.

AMA Style

Anisha Ghosh, Steven C. Ricke, Giselle Almeida, Kristen E. Gibson. Combined Application of Essential Oil Compounds and Bacteriophage to Inhibit Growth of Staphylococcus aureus In Vitro. Current Microbiology. 2015; 72 (4):426-435.

Chicago/Turabian Style

Anisha Ghosh; Steven C. Ricke; Giselle Almeida; Kristen E. Gibson. 2015. "Combined Application of Essential Oil Compounds and Bacteriophage to Inhibit Growth of Staphylococcus aureus In Vitro." Current Microbiology 72, no. 4: 426-435.

Evaluation study
Published: 25 July 2015 in Journal of Applied Microbiology
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Human norovirus (HuNoV) is estimated to cause 19–21 million illnesses each year in the US. A major limitation in HuNoV research is the lack of an in vitro culture system; therefore, surrogate viruses including murine norovirus (MNV) and feline calicivirus (FCV) are used to study HuNoV. Here, we aim to establish the physiochemical properties of Tulane virus (TV)—a newer HuNoV surrogate. For thermal inactivation, TV was exposed to 37°C for 2 h, and 56, 63 and 72°C for 30 min. For ethanol tolerance, TV was treated with 60, 70 and 90% ethanol at room temperature (RT) for 5 min. Tulane virus pH stability at pH 2, 3, 7, 9 and 10 was performed at RT for 90 min. At 37°C, there was no significant reduction in TV after 2 h. However, at 56, 63 and 72°C, D-values of 4·03, 1·18, and 0·24 min, were calculated respectively. The D-values obtained for TV ethanol tolerance were 1·46, 1·93, and 0·35 min at 60, 70 and 90% respectively. Less than 1 log10 plaque forming units (PFU) reduction was observed for TV at all pH levels except pH 10 where about a 2-log10 PFU reduction was observed. Tulane virus was also tolerant to chlorine disinfection on a solid surface with D-values of 15·82 and 5·42 min at 200 and 1000 ppm respectively. Tulane virus is likely a suitable surrogate to study HuNoV thermal stability as well as ethanol tolerance below 90%. Tulane virus also is a promising surrogate to study HuNoV pH stability and chlorine tolerance. Based on current work, in vitro studies demonstrate that TV is an overall more conservative and suitable surrogate for the study of HuNoV physicochemical properties.

ACS Style

S.E. Arthur; K.E. Gibson. Physicochemical stability profile of Tulane virus: a human norovirus surrogate. Journal of Applied Microbiology 2015, 119, 868 -875.

AMA Style

S.E. Arthur, K.E. Gibson. Physicochemical stability profile of Tulane virus: a human norovirus surrogate. Journal of Applied Microbiology. 2015; 119 (3):868-875.

Chicago/Turabian Style

S.E. Arthur; K.E. Gibson. 2015. "Physicochemical stability profile of Tulane virus: a human norovirus surrogate." Journal of Applied Microbiology 119, no. 3: 868-875.

Journal article
Published: 15 June 2015 in Applied and Environmental Microbiology
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Human noroviruses (HuNoVs) are the most common cause of food-borne disease outbreaks, as well as virus-related waterborne disease outbreaks in the United States. Here, we hypothesize that common free-living amoebae (FLA)—ubiquitous in the environment, known to interact with pathogens, and frequently isolated from water and fresh produce—could potentially act as reservoirs of HuNoV and facilitate the environmental transmission of HuNoVs. To investigate FLA as reservoirs for HuNoV, the interactions between two Acanthamoeba species, A. castellanii and A. polyphaga , as well as two HuNoV surrogates, murine norovirus type 1 (MNV-1) and feline calicivirus (FCV), were evaluated. The results showed that after 1 h of amoeba-virus incubation at 25°C, 490 and 337 PFU of MNV-1/ml were recovered from A. castellanii and A. polyphaga , respectively, while only few or no FCVs were detected. In addition, prolonged interaction of MNV-1 with amoebae was investigated for a period of 8 days, and MNV-1 was demonstrated to remain stable at around 200 PFU/ml from day 2 to day 8 after virus inoculation in A. castellanii . Moreover, after a complete amoeba life cycle (i.e., encystment and excystment), infectious viruses could still be detected. To determine the location of virus associated with amoebae, immunofluorescence experiments were performed and showed MNV-1 transitioning from the amoeba surface to inside the amoeba over a 24-h period. These results are significant to the understanding of how HuNoVs may interact with other microorganisms in the environment in order to aid in its persistence and survival, as well as potential transmission in water and to vulnerable food products such as fresh produce.

ACS Style

Tun-Yun Hsueh; Kristen E. Gibson. Interactions between Human Norovirus Surrogates and Acanthamoeba spp. Applied and Environmental Microbiology 2015, 81, 4005 -4013.

AMA Style

Tun-Yun Hsueh, Kristen E. Gibson. Interactions between Human Norovirus Surrogates and Acanthamoeba spp. Applied and Environmental Microbiology. 2015; 81 (12):4005-4013.

Chicago/Turabian Style

Tun-Yun Hsueh; Kristen E. Gibson. 2015. "Interactions between Human Norovirus Surrogates and Acanthamoeba spp." Applied and Environmental Microbiology 81, no. 12: 4005-4013.

Comparative study
Published: 20 December 2014 in Food and Environmental Virology
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Human enteric viruses have been identified as one of the predominant causative agents of food-borne illnesses in developed countries, and it is estimated that human norovirus accounts for a majority of these illnesses each year. Not all of these viruses can be cultured and hence relatively little is known about their pathogenesis and physicochemical properties. To overcome this, researchers have utilized different virus surrogates for the study of non-cultivable human enteric viruses. In this review, we discuss various methods utilized for the evaluation of the thermal stability of human enteric viruses, compare the results of these methods, and examine how researchers may move toward a single standard approach (i.e., temperatures, virus concentrations, volume/weight of matrices, etc.) for determining thermal inactivation profiles of human enteric viruses and their surrogates. Based on our review, we found that temperature, time of exposure, type of matrix, analysis type, type of heat application, and the concentration and volume of virus used in the experiments were highly variable across virus surrogates even for the same surrogates. Because of these differences-along with the inherent limitations of using surrogate viruses-comparison of these methods and how the results may be extrapolated to human enteric viruses is quite challenging. As a result, we discuss how researchers may move toward a single standard approach for determining thermal inactivation profiles of human enteric viruses and their surrogates.

ACS Style

Sabastine E. Arthur; Kristen E. Gibson. Comparison of Methods for Evaluating the Thermal Stability of Human Enteric Viruses. Food and Environmental Virology 2014, 7, 14 -26.

AMA Style

Sabastine E. Arthur, Kristen E. Gibson. Comparison of Methods for Evaluating the Thermal Stability of Human Enteric Viruses. Food and Environmental Virology. 2014; 7 (1):14-26.

Chicago/Turabian Style

Sabastine E. Arthur; Kristen E. Gibson. 2014. "Comparison of Methods for Evaluating the Thermal Stability of Human Enteric Viruses." Food and Environmental Virology 7, no. 1: 14-26.