Food Microbiology Commons^™

Assessment Of Salmonella Enterica Biofilms And Expression Differences Among Serovars, Zhaohao Shi

Graduate Theses and Dissertations

Biofilms are communities of microorganisms associated by a matrix of extracellular polymers. In this state, microorganisms occupy an ecological niche distinct from their free-floating, planktonic counterparts. Also, biofilm bacteria become biologically unique as they form communities and lose motility. The acquisition of these physiological attributes enables the biofilm to persist through harsh environmental conditions, including antimicrobial induced stress and to resist sanitization efforts. Because of these features, biofilms can rapidly disseminate across numerous surfaces and as they establish, become challenging to remove. This is a particular issue for the food industry as processing plants offer favorable conditions for biofilm formation …

Efficacy Of Natural Compounds With Novel Carrier Systems For Controlling Campylobacter Jejuni In Post-Harvest Poultry, Sandip Shrestha

Graduate Theses and Dissertations

Campylobacter jejuni, a leading cause of bacterial gastroenteritis worldwide, is strongly associated with the consumption and/or mishandling of raw contaminated poultry products. Thus, interventions aiming to reduce C. jejuni counts on poultry products could greatly reduce the incidence of human campylobacteriosis. In the first study, the efficacy of a generally recongnized as safe (GRAS) compound, carvacrol (CR; derived from oregano oil), as an antimicrobial wash treatment to reduce C. jejuni on chicken skin was evaluated. Three delivery systems of CR: suspension, emulsion and nanoemulsion were used. C. jejuni counts were reduced up to 4 log10 cfu/sample by 2% dose of …

Aqueous Ozone Inactivation Of Viruses And Bacteria On Biotic And Abiotic Surfaces, Cailin Dawley

Graduate Theses and Dissertations

Produce is susceptible to contamination by foodborne pathogens. Food service establishments utilize sanitizing agents to reduce microbes on produce surfaces. The research objectives were to evaluate the efficacy of aqueous ozone 1) on the inactivation of viruses and bacteria on produce; 2) on the inactivation of viruses on stainless steel; and 3) against viruses in association with bacteria on produce surfaces. For objective 1, Boston bibb lettuce and cherry tomatoes were spot inoculated with a cocktail of viruses (murine norovirus (MNV) and MS2 bacteriophage) or bacteria (Enterobacter cloacae and Bacillus cereus) and washed for 40 min with samples taken every …

Efficacy Of Antimicrobial Mitigation On Escherichia Coli Cfu And Growth And Development Of Hydroponic Leafy Greens, Nathan J. Eylands

Graduate Theses and Dissertations

The Food and Drug Administration (FDA) have set new standards that apply to agriculturalists producing crops eaten fresh and/or raw by consumers. This new produce safety rule, known as the Food Safety Modernization Act (FSMA), has established science-based standards for all areas of production in agriculture with regards to microbial contamination. Escherichia coli (E. coli) O157:H7 is a particular bacterium of concern under FSMA guidelines. Grower compliance is mandatory and therefore vital to the continuation of any farm. Greenhouse hydroponic growers have shown advantages in efficiency when compared to conventional farming methodology. Those, however, with recirculating hydroponic systems face unique …

Microbiota Metabolic Product Deoxycholic Acid Prevents Campylobacter Jejuni Chicken Colonization Through Modulating Ceca Anaerobes, Bilal Ali Alrubaye

Graduate Theses and Dissertations

Campylobacter jejuni is a prevalent infectious enteritis mainly foodborne from chickens. Despite of reducing C. jejuni food contamination dramatically decreases campylobacteriosis, few effective approaches are available for the bacterial reduction in chickens. The aim of this study was to use microbial metabolic product deoxycholic acid (DCA) to reduce C. jejuni chicken colonization. Broiler chicks were fed 0 or 1.5 g/kg DCA, lithocholic acid (LCA), or urodeoxycholic acid (UDCA) in diets or orally gavaged with cholic acid (CA, 1.5g/kg body weight). Birds were also transplanted with DCA modulated anaerobes (DCA-Anearo) or aerobes (DCA-Aero). Birds were infected with 109 CFU/bird human clinical …

With-In Host Dynamics Of L. Monocytogenes And Thresholds For Distinct Infection Scenarios, Ashrafur Rahman, Daniel Munther, Aamir Fazil, Ben Smith, Jianhong Wu

Mathematics and Statistics Faculty Publications

The case fatality and illness rates associated with L. monocytogenes continue to pose a serious public health burden despite the significant efforts and control protocol administered by private and public sectors. Due to the advance in surveillance and improvement in detection methodology, the knowledge of sources, transmission routes, growth potential in food process units and storage, effect of pH and temperature are well understood. However, the with-in host growth and transmission mechanisms of L. monocytogenes, particularly within the human host, remain unclear, largely due to the limited access to scientific experimentation on the human population. In order to provide insight …

A Risk-Based Approach To Evaluate The Impact Of Interventions At Reducing The Risk Of Foodborne Illness Associated With Wheat-Based Products, Luis Sabillon

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Pathogens are emerging on previously unrecognized food vehicles, such as wheat flour, which is a widely consumed commodity. Despite its low water activity, wheat-based ingredients and products have been implicated in several foodborne outbreaks over the last few years, resulting not only in the recall of food products but also in consumer illnesses. As a raw agricultural commodity, wheat is exposed to naturally occurring microbiological contamination that may compromise the overall safety of flour and other derived products. To address the increased concern regarding the safety of wheat-based foods, the objectives of the present research study were designed to develop …

Experimental Evaluation Of The Importance Of Colonization History In Early-Life Gut Microbiota Assembly, Inés Martínez, Maria X. Maldonado-Gomez, João Carlos Gomes-Neto, Hatem Kittana, Hua Ding, Robert J. Schmaltz, Payal Joglekar, Roberto Jiménez Cardona, Nathan L Marsteller, Steven W. Kembel, Andrew K. Benson, Daniel A. Peterson, Amanda Ramer-Tait, Jens C. Walter

Department of Food Science and Technology: Faculty Publications

The factors that govern assembly of the gut microbiota are insufficiently understood. Here, we test the hypothesis that inter-individual microbiota variation can arise solely from differences in the order and timing by which the gut is colonized early in life. Experiments in which mice were inoculated in sequence either with two complex seed communities or a cocktail of four bacterial strains and a seed community revealed that colonization order influenced both the outcome of community assembly and the ecological success of individual colonizers. Historical contingency and priority effects also occurred in Rag1^-/- mice, suggesting that the adaptive immune system …

Concentration Of Listeria Monocytogenes In Skim Milk And Soft Cheese Through Microplate Immunocapture, Steven A. Rogers, Melissa Calicchia, Rosalee S. Hellberg

Food Science Faculty Articles and Research

Microplate immunocapture is an inexpensive method for the concentration of foodborne pathogens using an antibody-coated microplate. The objective of this study was to determine the efficacy of microplate immunocapture as an alternative to traditional enrichment for concentrating Listeria monocytogenes to levels detectable with selective plating or real-time PCR. L. monocytogenes isolates serologically characterized as Type 1 (1/2a) and Type 4 (untypeable) were grown overnight and diluted to 10⁰ to 10⁶ colony-forming units (CFU)/mL. The isolates were used to optimize microplate immunocapture in tryptic soy broth with 0.6% yeast extract (TSBYE), skim milk, and queso fresco samples. Following …

Advancing Risk Assessment: Mechanistic Dose-Response Modelling Of Listeria Monocytogenes Infection In Human Populations, Ashrafur Rahman, Daniel Munther, Aamir Fazil, Ben Smith, Jianhong Wu

Mathematics and Statistics Faculty Publications

Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. The utility of characterizing the effects of strain variation and individual/subgroup susceptibility on dose-response outcomes has motivated the search for new approaches beyond the popular use of the exponential dose-response model for listeriosis. While descriptive models can account for such variation, they have limited power to extrapolate beyond the details of particular outbreaks. By contrast, this study exhibits dose-response relationships from a mechanistic basis, quantifying key biological factors involved in pathogen-host dynamics. An …

Effect Of Grain Sorghum Polyphenols On Fecal Fermentation, Danielle Marie Ashley

Graduate Theses and Dissertations

Obesity is an increasing epidemic which during 2015-2016 afflicted 39.8% of adults and 18.5% of youth in the United States. Not only can obesity affect quality of life, but it can lead to life-threatening diseases such as type 2 diabetes, heart disease, stroke, and some cancers. Animal and human research have demonstrated a pattern of gut microbiota perturbation in overweight and obesity, characterized by a reduction of beneficial bacterial species and increase in harmful species. Diet has been established as a contributing factor in gut ecology, and foods including fiber, resistant starch, and polyphenols have been found to both enhance …

Implementation Of Iso/Iec Practices In Small And Academic Laboratories, Eric Layne Oliver

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Food Manufacturers are facing challenging times due to regulations such as the Food Safety Modernization Act (FSMA) requiring them to provide evidence they are producing safe foods. Food testing laboratories aid in the mitigation of food safety issues providing evidence that a manufacturers food safety system is acceptable. To perform these activities laboratories are required to adhere to certain standards such as ISO/IEC 17025 General Requirements for the Competence of Testing and Calibration Laboratories. However, implementation of ISO/IEC 17025 practices is challenging, especially for small and academic laboratories, due to lack of available guidance. A long-term goal of the University …

Thermal Inactivation Kinetics Of Salmonella Enterica And Enterococcus Faecium In Ground Black Pepper, Sabrina Vasquez

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Food safety concerns of low-a_wfoods have boosted, given the increased number of foodborne illnesses related to these products. Black pepper, among other spices, has been implicated in several outbreaks and recalls in recent years.Salmonella entericahas been identified as the causing agent of outbreaks of contaminated spices. Therefore, increased efforts should be conducted to ensure food safety of spices, including black pepper. Food Safety Modernization Act (FSMA) demands all food processing facilities to conduct proper validations of the decontamination technologies applied to food products. Complete thermal process validations require a deep understanding of the thermal inactivation kinetics …

Methane Emissions From Rice Production On A Silt-Loam Soil In Arkansas, Joshua Jeffry Humphreys

Graduate Theses and Dissertations

Methane (CH4) emissions from rice (Oryza sativa L.) production are a source of concern in the environmental and agricultural communities. New and/or revised agronomic methodologies will be needed to identify production practice combinations that reduce CH4 emissions without decreasing yields. The objective of this multi-year study was to evaluate the effects of water management (i.e., full-season flood and mid-season drain) (2015), cultivar (i.e., pure-line cultivar ‘LaKast’ and the RiceTec hybrid “XP753”) (2015), soil organic matter (SOM) concentration (2016), and tillage [conventional tillage (CT) and no-tillage (NT)] and urea-based fertilizers [N-(n-butyl) thiophosphoric triamide (NBPT)-coated urea and non-coated urea] (2017) on CH4 …

Investigating The Potential Of Plant-Derived Antimicrobials For Controlling Campylobacter Jejuni In Poultry And Poultry Products, Basanta Raj Wagle

Graduate Theses and Dissertations

Campylobacter jejuni infection in humans is strongly associated with the handling and consumption of contaminated poultry products. Interventions reducing C. jejuni contamination in poultry would reduce the risk of subsequent human infections. In the first study, the efficacy of a Generally Recognized as Safe (GRAS) compound, eugenol (EG; derived from cloves), as an antimicrobial dip treatment to reduce C. jejuni in postharvest poultry was evaluated. The antimicrobial efficacy of EG was studied in suspension, emulsion and nanoemulsion delivery systems. EG suspension reduced C. jejuni counts with the greatest reduction of >2.0 Log CFU/sample for the 2% dose of EG (P

Survival And Inactivation Of Salmonella Enterica And Human Norovirus On Consumer Contact Surfaces, Dorra Simmons

LSU Doctoral Dissertations

Salmonella enterica and human norovirus (HuNoV) are the leading cause of bacterial and viral gastroenteritis worldwide, respectively. One of the most important transmission routes of these pathogens is contaminated surfaces. In this study, we investigated the survival and the disinfection of Salmonella enterica serovar Typhimurium (S. Typhimurium) and HuNoV on selected consumer contact surfaces.

In the case of S. Typhimurium, formica laminate, stainless steel, and plastic cutting board surfaces were inoculated with different microbial loads of cells collected at log (6 h), stationary (24 h), or LTS (14 days) phases. The disinfection efficacy of two disinfectants (sodium hypochlorite or …

Delivering Entrapped Lactobacillus Plantarum Ncimb 8826 With Cereal-Legume Infant-Weaning Food To Improve Children's Gastrointestinal Health, Emmanuel Kyereh

LSU Doctoral Dissertations

Diarrhea remains the second leading cause of death among children under five globally, about one in five children’s deaths are attributable to it. In recent years,’ probiotics have been used as an alternative therapy measure to manage the situation. A promising delivery method that entraps probiotics in infant formula may help prevent or reduce diarrhea. The overall objectives of this study were to deliver entrapped Lactobacillus Plantarum NCIMB 8826 with maize-legume fortified complementary weaning food to reduce diarrhea and improve the gut microbiota. Both in vitro and in vivo models were used in this study and a mouse (C57BL/6 mice …

Microbiological Safety Assessment Of Fresh Fruits And Vegetables Collected From Main Markets Of Multan, Pakistan, Bina Rida, Farah Deeba

Journal of Bioresource Management

Most of the research related to food-borne human pathogens is conducted on the transmission of pathogens from foods of animal origin. However, recent studies showed that fruits and vegetables are the sources of many disease outbreaks. This study was carried out to assess the current knowledge and future developments for the microbial safety of fresh fruits and vegetables. The eight different fruits and vegetables, Grape (Vitis vinifera), Banana (Musa acuminate), Orange (Citrus sinensis), Apple (Malus domestica Borkh), Carrott (Daucus carota), Cucumber (Cucumis sativus), Green chili (Capsicum annuum …

Effect Of Gallic And Ferulic Acids On Oxidative Phosphorylation On Candida Albicans (A72 And Sc5314) During The Yeast-To-Hyphae Transition, Rehab Aldahash

Department of Food Science and Technology: Dissertations, Theses, and Student Research

Candida albicans is a dormant commensal in the mucosa of healthy individuals but can become an opportunistic pathogen when the host microflora is compromised. It has been reported as the most common cause of fungal infection among hospitalized U.S. patients, with elevated mortality rate. Candida species have been reported as resistant to antifungal drugs that increase the application of novel strategies to treat this infection. Among the natural compounds that have most gained attention as potential agents against fungi are phenolic compounds against fungi. C. albicans has the ability to switch phenotype from yeast-to-hyphae cells, with hyphae being the most …

Breeding For Resistance In California Strawberry To Verticillium Dahliae, Zachary Christman

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This article focuses on breeding resistant strawberries to the fungus Verticillium dahliae, common name Verticillium wilt. This is a serious fungal disease that can result in a loss of 50% or more of a strawberry harvest when grown in infested soil. The main goal is to provide an example of how a cultivar can be made more resistant to a plant pathogen with the use of plant breeding methods.

Since 1930 the University of California, Davis, has been developing strawberry cultivars that are adapted to the agricultural industry and regional farms. Developing cultivars that require fewer inputs are of …

Lignocellulosic Biorefineries In Europe: Current State And Prospects, Amit Jaiswal, Shady Hassan, Gwilym A. Williams

Articles

In 2012, the European Bioeconomy strategy was launched, defining the bioeconomy as "the 33 production of renewable biological resources and the conversion of these resources and waste 34 streams into value added products". This strategy and its action plans increased the turnover 35 of the total bioeconomy in the EU from 2.09 trillion Euro in 2008 to 2.29 trillion in 2015 .

Protein And Lipid Characterization Of Acheta Domesticus, Bombyx Mori, And Locusta Migratoria Dry Flours, Emily N. Brogan

Graduate Theses, Dissertations, and Problem Reports (ETD)

Cricket (Acheta domesticus), silkworm pupae (Bombyx mori), and locust (Locusta migratoria) dry flours were obtained to examine the biochemical properties and composition of the flours. This study aimed to characterize the protein and lipid components of three insect species utilizing proximate composition analyses, amino acid composition analysis, protein solubility, SDS-PAGE, fatty acid composition analysis, and thin layer chromatography to determine lipid classes, and lipid extraction efficiency. Kjeldahl determined the cricket, locust, and silkworm flours contained 72.0%, 53.1%, and 71.2% protein, respectively. All proximate composition analyses were significantly (p< 0.05) different between species. Amino acid composition analysis revealed that the flours contained 3.6-3.9% and 0.90-1.5% of lysine and methionine, respectively. Many countries have cereal grains and legumes as a staple in their diet that contain these limiting amino acids. Essential amino acids were 22% of total amino acids. Protein solubility revealed that the three species studied were most soluble in alkaline environments with highest protein solubility occurring at pH 13 at 66% solubility in silkworm. Lowest solubility occurred in more acidic conditions between pH 4-5. SDS-PAGE revealed five major protein fractions with estimated molecular weights of 27 (cuticle proteins), 41 (arginine kinase), which has been identified as an allergen in shrimp, 42 (actin), 71 (hemocyanin), and 220 myosin) kDa. Soxhlet extraction determined cricket, silkworm, and locust flours contained 15.4%, 33.3%, and 11.4% lipid, respectively. The only omega-3 fatty acid found in the flours was α-linolenic acid. Silkworm flour contained the most α-linolenic acid at 33.3% of total fatty acids, followed by locust (13.7%), and cricket (0.6%). TLC resolved lipids for typical lipid classes. The four major lipid classes noted were triacylglycerol, free fatty acid, cholesterol, and phospholipid. Lipid extraction efficiency found that the organic solvents chloroform and methanol had the highest lipid extraction yield in both cricket (69.3%) and locust (93.0%). Methyl-tertiary-butyl ether (MTBE) extracted lipids most efficiently in the silkworm. Proteins and lipids found in insects need to be isolated to further or commercial use.

Relationships Between Factors Influencing Biofilm Formation And Pathogen Retention In Complex Rhizosphere Microbial Communities, Aaron Coristine

Theses and Dissertations (Comprehensive)

Riparian wetlands are unique habitats facilitating all forms of life. The riverbanks of these environments provide ideal conditions for bacteria, plants, and higher organisms. Of particular interest to this research was the variation in microbial community structure at high, intermediate and poor water quality impacted areas. Assessing the capabilities of plants to retain microbial pathogens was identified. Root systems and corresponding soil are ideal locations for bacterial deposition, resulting in attachment at these areas. Biofilm production in these regions is important for long-term establishment, leading to persistence and potential naturalization. Opportunistic pathogens originating from mammalian fecal matter are introduced into …