VTechWorks Repository :: Browsing by Author "Ponder, Monica A."

Browsing by Author "Ponder, Monica A."

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Acetone, Butanol, and Ethanol (ABE) Production from Food Waste via Clostridium beijerinckii
Poe, Nicholas Edward (Virginia Tech, 2020-01-28)
Annually, approximately 150 million metric tonnes of food goes to waste in the U.S., potentially causing economic loss and environmental pollution. Fermentation of food waste to produce acetone, butanol and ethanol (ABE) via fermentation has the potential to valorize food waste by producing value-added chemicals. However, the composition of food wastes from different sources vary, which affects ABE fermentation performance and hinders the commercialization of food waste fermentation. The objective of this study is to investigate the compositional variation of food waste collected weekly for 16 weeks (a total of sixteen samples) and determine how this variation affects ABE fermentation performance. Samples collected from Southgate Center, a food processing facility operated by Virginia Tech Dining Services, was characterized for use as a feedstock for ABE fermentation. Water, sugar, starch, fiber, protein, fat and ash concentrations in each of food waste samples were determined. ABE fermentation of these wastes was performed using Clostridium beijerinckii via batch fermentations. Correlations of ABE and butanol yields with the individual components of food waste composition were performed to better understand which components are key to ABE fermentation. Overall, this study demonstrated the feasibility of using food waste as a viable feedstock for ABE fermentation and investigated the effect of variation of food waste composition on the ABE fermentation performance. In the 16 collected samples, each major compositional attribute exhibited high variability. The concentration of total soluble sugar, defined as glucose, fructose, sucrose for the purposes of this experiment, ranged from 0.5 to 53.5% (dry basis) among different food waste samples. The concentration ranges of total starch, neutral detergent fiber (NDF), crude protein, crude fat and ash were 0 to 23.4% (dry basis), 0.6 to 25.8%, 5.5 to 21.2%, 0.1 to 37.9%, 1.4 to 13.7%, respectively. The high variation of food waste composition resulted in a high variation of ABE yield when these food wastes were subjected to fermentation by C. beijerinckii. The total ABE concentration following fermentation ranged between 6.9 to 17.0 g/L with an average value of 13.2 g/L. ABE and butanol concentrations are positively correlated with starch and equivalent glucose, i.e., the sum of initial free glucose and glucose that could be theoretically hydrolyzed from starch and sucrose during fermentation, but is negatively correlated with NDF concentrations.
Alteration to Gastrointestinal Microbial Communities Associated with Increasing Fiber Digestibility
Klotz, Courtney Elizabeth (Virginia Tech, 2013-09-04)
Distillers dried grains with solubles (DDGS) is a byproduct of distillation. Its increased availability has led to research into overcoming the nutritional limitations of its high non-starch polysaccharide (NSP) content for use in monogastric animal feed. The purpose of this study was to examine the effects of two factors (the inclusion of DDGS and/or inclusion of a carbohydrase mixture) on the richness and abundance of swine gastrointestinal bacteria. The carbohydrase mixture was expected to aid digestion, leading to increased nutritional availability for the host while simultaneously shifting dominant communities within the gut microbiome. Ileal cannulated pigs (n = 8, BW = 64.3 +/-0.5 kg) were allotted to 4 dietary treatments in a replicated 4 x 4 Latin square design. Treatments resulted in changes to bacterial richness, and diets containing DDGS increased the 16S rDNA abundance of members of Bacteroides (P < 0.0001), Ruminococcus (P < 0.0001), the Clostridium coccoides group (P <0.0001), and the Clostridium leptum subgroup (P = 0.005). Significant interactions between diet and carbohydrases were determined for total bacteria in the ileal digesta (P = 0.01) and feces (P = 0.02), Bacteroides (P = 0.003), and the Clostrdium leptum subgroup (P = 0.03). The DDGS diet with the inclusion of the carbohydrases was able to maintain, or increase the abundance of fiber degrading bacteria while theoretically increasing nutrition for the host.
Amorphous solid dispersion effects on in vitro solution concentrations of quercetin
Gilley, Andrew (Virginia Tech, 2016-08-31)
Quercetin is a flavonol with potential health benefits including activities against cardiovascular disease, obesity, and oxidative stress. However, the benefits of quercetin are likely limited by poor bioavailability, primarily attributed to its poor aqueous solubility (due to its hydrophobicity and crystallinity) and extensive phase-II metabolism. Improving the apparent solubility of quercetin has the potential to improve its in vivo bioavailability. Strategies to increase solution concentrations in the small intestinal lumen have the potential to substantially increase quercetin bioavailability, and efficacy. We aimed to achieve this by incorporating quercetin into amorphous solid dispersions (ASDs) with cellulose derivatives, eliminating crystallinity, and selectively releasing amorphous quercetin under simulated intestinal conditions (pH 6.8, 37C). Amorphous quercetin was dispersed in cellulose esters including 6-carboxycellulose acetate butyrate (CCAB), hydroxypropylmethylcellulose acetate succinate (HPMCAS) and cellulose acetate suberate (CASub) to achieve stability and provide pH-triggered release. In addition, polyvinylpyrrolidone (PVP) containing CASub and CCAB blends were prepared to further promote enhanced dissolution. The ASD employing 10% quercetin in 20% PVP:70% CASub was most successful at enhancing the solution concentration of quercetin, providing an 18-fold increase in the area under the concentration/time curve (AUC) compared to quercetin alone. These results warrant in vivo assessment of quercetin-loaded ASDs formulated with CASub and its blend with PVP towards improving the bioavailability of quercetin.
Anthropogenic landscapes increase Campylobacter jejuni infections in urbanizing banded mongoose (Mungos mungo): A one health approach
Medley, Sarah; Ponder, Monica A.; Alexander, Kathleen A. (PLOS, 2020-03-17)
Background: Campylobacter is a common, but neglected foodborne-zoonotic pathogen, identified as a growing cause of foodborne disease worldwide. Wildlife and domestic animals are considered important reservoirs, but little is known about pathogen infection dynamics in free-ranging mammalian wildlife particularly in sub-Saharan Africa. In countries like Botswana, there is significant overlap between humans and wildlife, with the human population having one of the highest HIV infection rates in the world, increasing vulnerability to infection. Methodology/Principal findings: We investigated Campylobacter occurrence in archived human fecal samples (children and adults, n = 122, 2011), feces from free-ranging banded mongooses (Mungos mungo, n = 201), surface water (n = 70), and river sediment samples (n = 81) collected in 2017 from the Chobe District, northern Botswana. Campylobacter spp. was widespread in humans (23.0%, 95% CI 13.9–35.4%), with infections dominantly associated with C. jejuni (82.1%, n = 28, 95% CI 55.1–94.5%). A small number of patients presented with asymptomatic infections (n = 6). While Campylobacter spp. was rare or absent in environmental samples, over half of sampled mongooses tested positive (56%, 95% CI 45.6–65.4%). Across the urbanwilderness continuum, we found significant differences in Campylobacter spp. detection associated with the type of den used by study mongooses. Mongooses utilizing man-made structures as den sites had significantly higher levels of C. jejuni infection (p = 0.019) than mongooses using natural dens. Conversely, mongooses using natural dens had overall higher levels of detection of Campylobacter at the genus level (p = 0.001). Conclusions: These results suggest that landscape features may have important influences on Campylobacter species exposure and transmission dynamics in wildlife. In particular, data suggest that human-modified landscapes may increase C. jejuni infection, a primarily human pathogen, in banded mongooses. Pathogen circulation and transmission in urbanizing wildlife reservoirs may increase human vulnerability to infection, findings that may have critical implications for both public and animal health in regions where people live in close proximity to wildlife.
Antibiotic Susceptibility of non-pathogenic Escherichia coli from meat and produce available in the Chobe region of Botswana
Saunders, Rachel; Bywater, Auja L.; Fleming, Madison; Kelly, Christine; Nuckolls, Evan; Alexander, Kathleen A.; Ponder, Monica A. (2023-04-21)
Antimicrobial Resistance Mitigation [ARM] Concept Paper
Vikesland, Peter J.; Alexander, Kathleen A.; Badgley, Brian D.; Krometis, Leigh-Anne H.; Knowlton, Katharine F.; Gohlke, Julia M.; Hall, Ralph P.; Hawley, Dana M.; Heath, Lenwood S.; Hession, W. Cully; Hull, Robert Bruce IV; Moeltner, Klaus; Ponder, Monica A.; Pruden, Amy; Schoenholtz, Stephen H.; Wu, Xiaowei; Xia, Kang; Zhang, Liqing (Virginia Tech, 2017-05-15)
The development of viable solutions to the global threat of antimicrobial resistance requires a transdisciplinary approach that simultaneously considers the clinical, biological, social, economic, and environmental drivers responsible for this emerging threat. The vision of the Antimicrobial Resistance Mitigation (ARM) group is to build upon and leverage the present strengths of Virginia Tech in ARM research and education using a multifaceted systems approach. Such a framework will empower our group to recognize the interconnectedness and interdependent nature of this threat and enable the delineation, development, and testing of resilient approaches for its mitigation. We seek to develop innovative and sustainable approaches that radically advance detection, characterization, and prevention of antimicrobial resistance emergence and dissemination in human-dominated and natural settings...
Application of Far Infrared Radiation and Ethanol Vapor as Alternative Treatment Methods for Reduction of Salmonella enterica Tennessee in Dried, Ground Spices
Nimitz Jr, Stephen Clark (Virginia Tech, 2013-05-24)
The consumption of spiced food is steadily increasing, subsequently leading to increased incidence of spice-related food illnesses. Many outbreaks can be traced to human pathogens that can survive in low moisture content of spices, prompting development of additional inactivation treatments that reduce bacterial pathogens while maintaining spice quality. Spices are currently treated by fumigation with ethylene oxide, pasteurization with ionizing radiation, or steam treatment. However, these treatments exhibit flaws pertaining to consumer preference, regulatory issues, and quality degradation. In this study, two novel treatments were evaluated for reduction of Salmonella enterica Tennessee: far infrared radiation (FIR), a short time â " high temperature treatment, and pasteurization with ethanol vapor (EV). Both treatments were effective in reducing levels of Salmonella Tennessee between 3-5 logs. FIR treatment showed increased efficacy at longer treatment times with a maximum reduction of 5 log CFU/g in paprika at 24s. EV reduced Salmonella Tennessee by 3 log CFU/g within 120s when applied to inoculated paprika and black pepper without detrimentally affecting spice quality. However, the samples receiving FIR treatments suffered reductions in volatile content and color changes to the spices. High levels (up to 1% w/w) of residual ethanol were also detected on samples treated for 300s. Concluding, both treatment show similar results when comparing efficacy; however, based on the magnitude of change in volatile content associated with FIR being significantly greater than those samples receiving EV, FIR treatment requires additional research before recommending for use with dried, ground paprika, black pepper, or sage.
Association of Campylobacter spp. Levels between Chicken Grow-Out Environmental Samples and Processed Carcasses
Schroeder, Matthew William (Virginia Tech, 2012-04-20)
Campylobacter spp. have been isolated from live poultry, production environment, processing facility, and raw poultry products. The detection of Campylobacter using both quantitative and qualitative techniques would provide a more accurate assessment of pre- or post harvest contamination. Environmental sampling in a poultry grow-out house, combined with carcass rinse sampling from the same flock may provide a relative assessment of Campylobacter contamination and transmission. Air samples, fecal/litter samples, and feed pan/drink line samples were collected from four commercial chicken grow-out houses. Birds from the sampled house were the first flock slaughtered the following day, and were sampled by post-chill carcass rinses. Quantitative (direct plating) and qualitative (direct plating after enrichment step) detection methods were used to determine Campylobacter contamination in each environmental sample and carcass rinse. Campylobacter, from post-enrichment samples, was detected from 27% (32/120) of house environmental samples and 37.5% (45/120) of carcass rinse samples. All sample types from each house included at least one positive sample except the house 2 air samples. Samples from house 1 and associated carcass rinses accounted for the highest total of Campylobacter positives (29/60). The fewest number of Campylobacter positives, based on both house environmental (4/30) and carcass rinse samples (8/30) were detected from flock B. Environmental sampling techniques provide a non-invasive and efficient way to test for foodborne pathogens. Correlating qualitative or quantitative Campylobacter levels from house and plant samples may enable the scheduled processing of flocks with lower pathogen incidence or concentrations, as a way to reduce post-slaughter pathogen transmission.
Association of Salmonella enterica serotype Newport with Tomato Plants through Irrigation Water, Grown under Controlled Environmental Conditions
Hintz, Leslie Diane (Virginia Tech, 2008-11-21)
Tomato fruit have been associated with numerous outbreaks of salmonellosis in recent years. Trace back suggests tomato fruit may become contaminated during pre-harvest, however exact routes are unclear. The objective of this study was to determine the potential for Salmonella enterica serotype Newport to be associated with the roots, leaves, stems, and ultimately fruit of red round tomato plants through contaminated irrigation water, at various stages of plant development, when grown under controlled environmental conditions. Tomato plants were individually root irrigated with 250 or 350 ml (depending on growth stage) of 7 log CFU/ml S. Newport contaminated irrigation water every seven days. Presence of the pathogen in plant tissue was evaluated at five growth stages; 14 days post transplant, early fruit, mid fruit, full fruit, and terminal stages. At each stage, roots, stems, leaves, and two tomato fruit, if present, from four S. Newport and four water irrigated (negative control) tomato plants were sampled for S. Newport contamination. Association of S. Newport was detected in tomato roots and stems using both conventional plating and molecular techniques. Twenty-four samples were confirmed positive for S. enterica using PCR. Sixty-five percent of the roots, 40% of the stems, 5% of the leaves and 5% of the fruit sampled were confirmed to contain S. enterica. Overall, there was significant difference in the presence of S. Newport according to tissue sampled (roots > stems > leaves and fruit) (P > 0.05). There was no correlation between growth stage and presence of S. Newport in tissues (P > 0.05). Ultimately, irrigation with S. Newport has a low probability of contaminating tomato fruit.
Bridging the CGMP Gap Between the U.S. Government, Academia, and the Food Industry
West, Joey (Virginia Tech, 2012-12)
In communication theory, one of the most important aspects is to always remember who the audience is at all times. In this case, the audience are members of the food industry who are expected to translate the knowledge of the CGMPs into practice. The goal of this research is twofold; to effectively communicate the need and nature of the CGMPs and to simply reconnect the regulations to the audience they were developed to assist. Further, a definition of perception is an individual’s capacity for comprehension. We find that in the real world, an individual’s comprehension does not always neatly fit inside the perimeters that the CGMPs provide. In some cases compliance with regulations does not allow for continuation of traditional processing methods, short-cuts, and individual bias when it comes to how firms may prepare, process, hold, and ship food products. That leaves it up to the government to find a means to bridge the gaps that exist between comprehension, perception, and reality. The main focus is to present information so that the ordinary person can understand and act upon the regulation on a consistent basis. The answer may lay not in the regulation itself, but Food Industry members’ ability to relate to and understand the need for compliance.
Campylobacter in aquatic and terrestrial mammals is driven by life traits: A systematic review and meta-analysis
Brooks, Michael R.; Medley, Sarah; Ponder, Monica A.; Alexander, Kathleen A. (Frontiers, 2023-02)
Introduction: Campylobacter spp. infections are responsible for significant diarrheal disease burden across the globe, with prevalence thought to be increasing. Although wild avian species have been studied as reservoirs of Campylobacter spp., our understanding of the role of wild mammalian species in disease transmission and persistence is limited. Host factors influencing infection dynamics in wild mammals have been neglected, particularly life traits, and the role of these factors in zoonotic spillover risk is largely unknown. Methods: Here, we conducted a systematic literature review, identifying mammalian species that had been tested for Campylobacter spp. infections (molecular and culture based). We used logistic regression to evaluate the relationship between the detection of Campylobacter spp. in feces and host life traits (urban association, trophic level, and sociality). Results: Our analysis suggest that C. jejuni transmission is associated with urban living and trophic level. The probability of carriage was highest in urban-associated species (p = 0.02793) and the most informative model included trophic level. In contrast, C. coli carriage appears to be strongly influenced by sociality (p = 0.0113) with trophic level still being important. Detection of Campylobacter organisms at the genus level, however, was only associated with trophic level (p = 0.0156), highlighting the importance of this trait in exposure dynamics across host and Campylobacter pathogen systems. Discussion: While many challenges remain in the detection and characterization of Camploybacter spp., these results suggest that host life traits may have important influence on pathogen exposure and transmission dynamics, providing a useful starting point for more directed surveillance approaches.
Campylobacter jejuni and Salmonella spp. Detection in Chicken Grow Out Houses by Environmental Sampling Methods
Kuntz, Thomas James (Virginia Tech, 2009-04-24)
Campylobacter and Salmonella are foodborne pathogens commonly associated with raw poultry. Although there has been much research done on isolating these pathogens from poultry production environments using cloacal swabs, fecal samples, intestinal tract contents and dissection, research involving environmental sampling has been limited. New and/or improved environmental sampling methods may provide an easy, convenient, and less time-consuming way to collect samples. Coupling these sampling methods with PCR may provide a relatively simple, rapid, and robust means of testing for foodborne pathogens in a chicken house or flock prior to slaughter. Air, boot and sponge samples were collected from three commercial chicken grow-out houses located in southwestern Virginia when flocks were three, four, and five weeks old. Air samples were collected onto gelatin filters. Fecal/litter samples were collected from disposable booties worn over investigator's protective shoe coverings. Pre-moistened sponges were used to sample house feed pans and water dispensers on drink lines. A PCR method was used to qualitatively detect Campylobacter jejuni and Salmonella spp. Campylobacter jejuni was detected at each farm (house), across all three ages (3, 4, and 5 weeks), and from each sample type. Salmonella was not detected in any of the environmental samples. For all 270 samples, 41% (110/270) were positive for Campylobacter. Collectively, 28% (25/90) of air, 44% (40/90) of sponge, and 50% (45/90) of bootie samples were positive for Campylobacter. The methods used in this study are non-invasive to live animals, relatively rapid and specific, and could enable poultry processing facilities to coordinate scheduled processing of flocks with lower pathogen incidence, as a way to reduce post-slaughter pathogen transmission.
Changes in the gut microbial communities following addition of walnuts to the diet
Byerley, Lauri O.; Samuelson, Derrick; Blanchard, Eugene; Luo, Meng; Lorenzen, Brittany N.; Banks, Shelia; Ponder, Monica A.; Welsh, David A.; Taylor, Christopher M. (2017-10)
Walnuts are rich in omega-3 fatty acids, phytochemicals and antioxidants making them unique compared to other foods. Consuming walnuts has been associated with health benefits including a reduced risk of heart disease and cancer. Dysbiosis of the gut microbiome has been linked to several chronic diseases. One potential mechanism by which walnuts may exert their health benefit is through modifying the gut microbiome. This study identified the changes in the gut microbial communities that occur following the inclusion of walnuts in the diet. Male Fischer 344 rats (n=20) were randomly assigned to one of two diets for as long as 10 weeks: (1) walnut (W), and (2) replacement (R) in which the fat, fiber, and protein in walnuts were matched with corn oil, protein casein, and a cellulose fiber source. Intestinal samples were collected from the descending colon, the DNA isolated, and the V3-V4 hypervariable region of 16S rRNA gene deep sequenced on an Illumina MiSeq for characterization of the gut microbiota. Body weight and food intake did not differ significantly between the two diet groups. The diet groups had distinct microbial communities with animals consuming walnuts displaying significantly greater species diversity. Walnuts increased the abundance of Firmicutes and reduced the abundance of Bacteriodetes. Walnuts enriched the microbiota for probiotic-type bacteria including Lactobacillus, Ruminococcaceae, and Roseburia while significantly reducing Bacteroides and Anaerotruncus. The class Alphaproteobacteria was also reduced. Walnut consumption altered the gut microbial community suggesting a new mechanism by which walnuts may confer their beneficial health effects. (C) 2017 The Authors. Published by Elsevier Inc.
Characterization of Campylobacter, Salmonella, and Diarrheagenic Escherichia Coli from Food, Food Waste and Water in the Chobe Region of Botswana
Bywater, Auja L. (Virginia Tech, 2023-06-23)
Introduction and Justification: Diarrheal disease is a leading cause of death in children in low- and moderate-income countries. Food, food waste, and water are all vehicles that can promote the spread of diarrheal disease-causing bacteria like Campylobacter, Salmonella enterica, and E. coli. Resistance to commonly used antibiotics is on the rise, making them difficult to manage. This study aimed to determine prevalence and antibiotic resistance profiles of Campylobacter, S. enterica, and E. coli isolated from food, food waste, and water samples obtained from the Chobe Region of Botswana. In addition, the survival of two common pathogens, E. coli and C. jejuni, on kale, a type of leafy green commonly consumed raw, was determined. Methods: Samples were collected from the Chobe region of Botswana in 2022 including water from the local river, food (produce, beef, pork, and poultry) from local vendors, and food scraps from the landfill. Food samples were enriched in the appropriate selective media: Brilliant Green Bile Broth for E. coli, Bolton Broth for Campylobacter, and Rappaport Vassiliadis Broth for S. enterica. Water samples were collected using modified USEPA methods1103.1 and 1604, E.coli isolation was performed by plating on RAPID E.coli2 agar and incubation at 37°C for 2h and 44°C for 16-22h. Campylobacter, S. enterica, and E. coli were isolated from meat, poultry, and water samples before being sent to Virginia Tech, while enriched bacterial pellets from the produce were shipped for screening and isolation at Virginia Tech. E.coli were confirmed by PCR detecting the phoA gene (all E. coli), and classified as pathogenic through screening for the eae (present in enterohemorrhagic and enteropathogenic E.coli), stx1 and stx2 (present in enterohemorrhagic E. coli) and est1b ( present in Enterotoxigenic E.coli) genes. Campylobacter isolates were confirmed using a genera-specific PCR while S. enterica isolates were confirmed using invA primers. These enrichment and primer sets were tested as part of a study to determine the survival of E. coli O157:H7 and C. jejuni on kale during a 21-day shelf life. E. coli and S. enterica isolates were subjected to antibiotic resistance testing using the Kirby-Bauer Disk Diffusion method. Results: Methods for detection of inoculated E. coli O157:H7 on kale indicated survival for the majority of the shelf-life (up to 19 d), in comparison, C. jejuni was undetectable by day 13 using enrichment and PCR or plating. From the Botswanan samples, E. coli was isolated from 20% of produce, 49% of meat, and 84.7% of water. Salmonella was only isolated from produce samples (2.4%, 7/294). Resistance was uncommon among the Salmonella isolates with only one isolate being resistant to chloramphenicol. No Campylobacter were isolated from the screened produce, meat, or food waste. E. coli resistant to 3 or more classes of antibiotics (MCR) were identified in 15.5% of produce, and 22.2% of meat isolates. Isolation of E. coli or Salmonella from meat was not associated with a particular food type. In contrast, isolation of E. coli was more common from certain types of vegetables and fruits. Antibiotic-resistant E. coli were isolated more commonly from beef, poultry, and pork than from produce. Multi-class resistant E. coli were isolated from fruits, greens, soil associated, and above ground associated vegetables, beef, and poultry. Water samples were collected from the same time period as the food samples. E. coli isolation, especially pathogens (based on eae presence) was more frequent from environmental water samples collected during the wet season compared to the dry season. Water samples collected during periods of increased rainfall were more likely to contain E. coli isolates, especially pathogens. S. enterica and Diarrheagenic E. coli isolates, especially MCR isolates, pose a significant risk of illness to consumers. Strategies to reduce the circulation of these pathogens in foods and water sources are needed.
Characterization of Diarrheagenic Escherichia coli Isolated from Food, Food Waste, and Water from the Chobe Region of Botswana
Bywater, Auja L.; Ponder, Monica A.; Alexander, Kathleen A. (2023-04-21)
Colonic metabolism of dietary grape seed extract: Analytical method development, effect on tight-junction proteins, tissue accumulation, and pan-colonic pharmacokinetics
Goodrich, Katheryn Marie (Virginia Tech, 2015-03-31)
Procyanidins (PCs) have been extensively investigated for their potential health protective activities, but the prospective bioactivities are limited by their poor bioavailability. The majority of the ingested dose remains unabsorbed and reaches the colon where extensive microbial metabolism occurs. The objectives of these studies are to better understand the roles and activities of PCs in the lower gastrointestinal tract. First, a new high-throughput Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry method was developed to efficiently analyze PCs and an extensive profile of their microbial metabolites. This method is sufficiently sensitive and effective in simultaneously extracting and measuring native PCs and their microbial metabolites in biological samples. Furthermore, administration of grape seed extract increased the expression of gut junction protein occludin and reduced levels of fecal calprotectin, which suggests an improvement of gut barrier integrity and a potential modulation of endotoxemia. Additionally, chronic supplementation of the diet with flavanols did not increase colonic tissue accumulation of PCs or their microbial metabolites over a 12 week feeding study. This was the first long-term study of its kind, and the results indicate that we still do not fully understand the outcome of ingested flavanols in the colon during chronic exposure rather than acute doses. Lastly, new understanding of the microbial metabolism of PCs in the colon has been reached by studying the colon as 4 segments, rather than as a complete unit as previous studies have done. Data show that a gradient is established along the length of the colon for both PCs and their metabolites, with PCs reaching highest concentrations within 3 h after ingestion, while metabolites reach maximum concentrations anywhere form 3-18 h after ingestion. Moreover, data indicate the progressive, step-wise degradation of PCs into small metabolites throughout the length of the colon. Overall, there is greater understanding of the colonic metabolism of dietary PCs derived from GSE and cocoa, the accumulation of these compounds, and their effect on gut permeability. Future work will build off of these novel studies, and will continue to advance the understanding of the health benefits of dietary PCs.
The complexity of antibiotic resistance dynamics in scarce surface water resources in northern Botswana
Nkwalale, Lipa Gutani Terrence (Virginia Tech, 2020-09-03)
Antibiotic resistance (AR) is widely associated with intensive agricultural systems, pharmaceutical production, wastewater, and health facilities. However, little research has been conducted on AR gene (ARG) dynamics in natural environments lacking large-scale human inputs. In particular, we have a limited understanding of the complex dynamics influencing environmental AR in resource-limited dryland systems threatened by climate change. In northern Botswana, Escherichia coli isolates were obtained from river surface water (n = 426 samples; September 2017 – May 2018), sediments (n = 194; November 2017 – May 2018), and human fecal samples (n = 43 September 2017 and April 2018). A multiplex PCR assay was used to assess gene frequencies for sulfonamide (sul1 and sul2), tetracycline (tetA and tetB), and class 1 integron (intl1) resistance genes. The weighted frequency of sul1 in sediment E. coli isolates (µ= 0.07; SD = 0.39) was significantly higher than that observed in isolates obtained from surface water (µ= 0.03; SD = 0.15; p = 0.01). Weighted gene frequencies for sul1 and sul2 in human E. coli isolates from April 2018 were significantly higher than those in water (sul1 p = 0.01; sul2 p = 0.00) and sediment isolates (sul1 p = 0.01; sul2 p = 0.00) from the same time period. Significant differences for the five genes' weighted frequencies were observed between sampling months in water isolates (intl1 p = 3.318e-05; sul1 p = 3.217e-06; sul2 p = 4.392e-06; and tetA p = 2.477e-05), while only intl1 frequency differed significantly between months in sediment isolates (p = 0.05). While no significant spatial patterns of ARG frequencies were observed in E. coli isolates from water samples (p = 0.16), higher ARGs were observed in E. coli isolated from human-dominated land areas for intl1 (µ = 0.10; SD = 0.31) than in protected landscapes intl1 (µ = 0.03; SD = 0.13; p = 0.02). Land use also was associated with higher weighted frequencies for tetA in E. coli isolates from water in human-dominated land areas (µ = 0.10; SD = 0.30) compared to protected areas (µ = 0.04; SD = 0.23, p = 0.03). These results indicate that the interactions between land use and season-dependent hydrometeorological factors drive frequencies of some ARGs across this system, but do not fully explain the complexities observed. However, the lack of higher weighted gene frequencies for riverbed sediments suggests that they do not act as a reservoir for ARGs in the system, implicating humans as significant contributors to ARG persistence in the aquatic system.
Decision Making Tools for Optimizing Environmental Sampling Plans for Listeria in Poultry Processing Plants
Al Wahaimed, Abdullah Saud (Virginia Tech, 2022-07-08)
Meat and poultry slaughtering and processing practices have been associated with the microbial contamination with Listeria spp. Ready-to-eat poultry products have been considered as a primary agent associated with Listeria monocytogenes illness outbreaks. Developing environmental monitoring programs (EMPs) that are based on product and/or process risk level analysis is a useful approach to reduce contamination in poultry processing plants and enhance food safety. Sampling criteria that is based on product risk levels and process control in ready-to-eat poultry processing facilities was developed to allow users to design and conduct appropriate sampling plans to target Listeria spp. After developing the criteria, an internet-based environmental monitoring program ("EZSafety") was developed to allow poultry producers to enhance their sample collection and analysis of test results over time and conduct appropriate sampling plans for Listeria spp. and other microbiological indicators. The frontend of the program website was built using React Native (an open-source JavaScript library for building user interfaces). The backend of the program website was built using Node.js which executes JavaScript code outside a web browser. MongoDB was used as a document-oriented database for the website. The program was evaluated by 20 food safety professionals to assess its ability to develop appropriate sampling plans to target Listeria spp. The majority of these participants believed that EZSafety has several tools that are effective for targeting Listeria spp. and other indicators and enhancing environmental monitoring. Additionally, most participants agreed that EZSafety is organized and user-friendly. EMPs can play a significant role in improving the detection rate and the prevention of Listeria spp. and other indicators in poultry processing plants.
Effect of a Fermented Yeast Product on the Gastrointestinal Tract Microbial Diversity of Weaned Pigs Challenged With Salmonella Enterica Typhimurium Dt104
Totty, Heather Renae (Virginia Tech, 2009-11-13)
Gastrointestinal tract (GIT) microorganisms play important roles in animal health, including providing energy and vitamins, improving the host immune response and preventing pathogenic microorganisms from colonizing. Prebiotic feed supplementation offers an alternative to antimicrobial growth promoters by stimulating key populations of the GIT bacteria that can ferment these non-digestible compounds, producing various short chain fatty acids used by the animal. The objective of this study was to quantify the effects of a proprietary Saccharomyces cerevisiae fermentation product (XPC, Diamond V Mills, Inc., Cedar Rapids, IA) inclusion in nursery diets on the microbial diversity and growth performance of pigs before, during and after an oral challenge with Salmonella. Pigs (n= 40) were weaned at 21 d of age, blocked by body weight (BW) and assigned in a 2Ã 2 factorial arrangement consisting of diet (control or 0.2% XPC) and inoculation (broth or Salmonella). Diet had no effect on pig growth performance prior to inoculation; however, consumption of XPC altered the composition of the gastrointestinal microbial community resulting in increased growth performance prior to inoculation. After Salmonella infection, XPC altered the composition of the gastrointestinal microbial community resulting in increased (P < 0.05) populations of Bacteroidetes and Lactobacillus. Infection with Salmonella and treatment of the piglets with ceftiofur-HCl resulted in alterations to the species richness and abundance of key members of the GIT community. The addition of XPC to the diets of weaning pigs results in greater compensatory gains after infection with Salmonella and an increase in beneficial bacteria within the GIT.
Effect of Anaerobic Soil Disinfestation on Salmonella Concentration Using Different Soil Amendments
Marik, Claire Margaret (Virginia Tech, 2020-05-21)
Salmonella has been shown to survive in soils for extended periods. Anaerobic soil disinfestation (ASD) represents a promising alternative to fumigation used to manage soilborne diseases and pests; however, little is known about ASD's impact on Salmonella. The study aimed to compare Salmonella die-off following inoculation in ASD and non-ASD processed soil and compare Salmonella die-off in amended and non-amended soils following ASD. Two independent experiments were arranged in randomized complete block designs (four replications per treatment). Sandy-loam soil was inoculated with a Salmonella cocktail (5.5±0.2 log CFU/g) and amended with field-applicable rates of rye (R), rapeseed (RS), hairy vetch (HV), or pelletized poultry litter (PPL). Non-amended, anaerobic (ANC) and non-amended, aerobic controls (AC) were performed in parallel. Soils were irrigated to saturation and covered with plastic mulch. ASD was terminated by removal of plastic (3-weeks). Triplicate soil samples were collected pre-ASD and 0, 1, 2, 3, 7, 10, 14, 21, 28, 31, 35, 38 and 42d post-ASD. Post-ASD soil was irrigated weekly. Salmonella was quantified using standard methods and a modified MPN enrichment protocol. Concentrations between treatments and time-points were analyzed for significance (P≤0.05). Separate log-linear models were used to examine effect of amendment and irrigation on Salmonella die-off during ASD and post-ASD. Salmonella concentrations decreased in all treatments during ASD with the greatest decrease being observed in ASD and non-ASD controls. Among ASD-processed, amended soil, the rye and rapeseed amendments had the greatest decrease in Salmonella concentrations. Salmonella concentrations decreased by ~1 log between pre-ASD and post-soil saturation (95% Confidence Interval (CI) =-1.31, -0.99), and by approximately 2 logs between pre-ASD and termination of ASD (CI=-2.14, -1.83). Salmonella concentrations were ~1 log higher in ASD-processed, pelletized poultry litter-amended soil, compared to the ASD control (CI=0.81, 1.26). The average daily die-off rate of Salmonella post-ASD was -0.05 log per g (CI=-0.05, -0.04). Following irrigation, Salmonella concentrations were 0.14 log greater, compared to no irrigation within 7 d (CI=0.05, 0.23). Salmonella serovar distribution differed by treatment, with >70% survival of Newport in pelletized poultry litter. ASD does not eliminate Salmonella concentrations in soil; instead some amendments may enhance Salmonella survival.

Browsing by Author "Ponder, Monica A."

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