Digital Commons Network^™

A Multi-State Molecular Epidemiological Survey Of 16 Beef, Dairy, Poultry And Swine Farms To Facilitate Risk Assessment Of Listeria Monocytogenes, David Dean Rasmussen

Doctoral Dissertations

Listeria monocytogenes s an intracellular pathogen that poses serious risks for immuno-compromised individuals. On the farm risk assessment is needed to reduce exposure of such individuals to this pathogen. Base line epidemiological surveys for this pathogen are needed to identify common ecological reservoirs and sources. A 21 month survey of 4 animal farm types for L. monocytogenes in five different states was conducted to determine the level of occurrence in various environments. An overall occurrence of 1.4% (20/1432 samples) for L. monocytogenes was observed in this 21 month survey. Each sample type (soil, bedding/litter, feed/grass and animal rectal swabs) produced …

Antimicrobial Activity And Effect Of Selected Essential Oil Components On Cell Membrane Lipids, Valerie W. Ling

Doctoral Dissertations

The objectives of this study were to evaluate the antimicrobial activity of essential oil components (EOC) against Salmonella Typhimurium and Listeria monocytogenes and evaluate changes in bacterial membrane composition by observing changes in the fatty acids of Salmonella associated with exposure and adaptation to (or growth in the presence of) cinnamaldehyde (CIN) and carvacrol (CRV) EOC. Ten EOC were tested for efficacy using the broth microdilution and macrodilution methods. Beta-caryophyllene, limonene, alpha-pinene, and thymol were not lethal to Salmonella and Listeria at 2800mg/L. Dose-response models showed that the most effective EOC against Salmonella were CIN and CRV (50% probability of …

Occurrence Of Escherichia Coli0157:H7 In Diverse Farm Environments In Five States, Carl Andrew Doane

Masters Theses

In the United States, foodborne outbreaks of Escherichia coli O157:H7 illness have often been linked to the consumption of contaminated, undercooked ground beef. However, the occurrence of E. coli O157:H7 in other animals has also been reported. The objective of this study was to determine the occurrence of E. coli O157:H7 in cattle, swine, poultry, and farm environments. Environmental samples (n=576) and fecal swab samples (n=1686) from sixteen locations in the U.S. were collected over 22 months. Overall, in fecal swabs E. coli O157:H7 was positive (serologically confirmed) in 4.7% of beef cattle (n = 408), 3.9% of dairy cattle …

Physicochemical And Antimicrobial Properties Of Antimicrobials Encapsulated In Surfactant-Based Nanoparticles, Sylvia Gaysinksy Segura

Masters Theses

Phytophenols, components of essential oil extracts, are antimicrobials that may inhibit the growth of foodborne pathogens. However, their antimicrobial activity in food systems is low because of low water solubility and association with other food components. Incorporation of phytophenols in nanoscale surfactant micelles may offer a potential solution to increase solubility and improve activity in food systems. The objectives of this study were to determine the stability and physicochemical and antimicrobial properties of micellar antimicrobial-surfactant systems.

Carvacrol and eugenol containing micelles were prepared by dispersing Surfynol^® 485W and Surfynol^® 465 in water at room temperature. Stability was determined …

Antimicrobial Activity Of Trypsin And Pepsin Hydrolysates Derived From Acid-Precipitated Bovine Casein, Kellie Parks Burris

Masters Theses

Foodborne pathogens are a major concern to the food industry and consumers but they may be controlled with antimicrobials. Naturally occurring antimicrobials may be isolated from a variety of plant, animal and microbial sources. Previous studies have demonstrated that peptides isolated from enzyme hydrolyzed milk proteins may have in vivo and in vitro antimicrobial activity. Such compounds could be of use as inhibitors of foodborne pathogens. The objectives of this study were to determine the antimicrobial effectiveness against Salmonella Typhimurium and Listeria monocytogenes of digests of bovine acid-precipitated casein with the enzymes pepsin and trypsin and to determine if these …

Development And Characterization Of Antimicrobial Food Coatings Based On Chitosan And Essential Oils, Shuang Chi

Masters Theses

The objectives of this research were (1) to evaluate antimicrobial effects of essential oils incorporated in chitosan edible films against Listeria monocytogenes and Escherichia coli O157:H7, (2) to evaluate effectiveness of the films on a meat product, (3) to characterize physical properties of chitosan films enriched with essential oils, and (4) to determine whether the addition of oregano essential oil to bologna can influence consumer liking of the product.

Anise, basil, coriander, and oregano essential oils were tested for antimicrobial activity by paper disc diffusion test with concentration of 1 to 24 ml/disc. Chitosan films incorporated with those essential oils …

High-Intensity Ultrasound Mediated Structure-Function Changes Of Bsa As Affected By Ph, İbrahim Gülseren

Masters Theses

The influence of high intensity ultrasound on the structure-function relationship of BSA sonicated at various sonication times at neutral, acidic and basic pH was determined. Protein solutions (3 x 10^-4 M) were treated with high-intensity ultrasound at an ultrasonic intensity of 20 Wcm^-2 with treatment times ranging from 0 to 90 minutes. Changes in structure-function properties of BSA were monitored using a wide variety of biochemical and physicochemical analytical methods including interfacial tensiometry, free sulfhydryl group assays, zeta potential analysis, hydrophobicity assays, circular dichroism spectroscopy, micro DSC and FTIR. The results were attributed to mechanical and chemical changes …

Atmospheric Plasma Inactivation Of Foodborne Pathogens On Fresh Produce Surfaces, Faith Michelle Johnson

Masters Theses

A study was conducted to determine the effect of a one atmosphere uniform glow discharge plasma (OAUGDP) on inactivation of nalidixic acid resistant Escherichia coli O157:H7 and Salmonella, and Listeria monocytogenes on apples, cantaloupe, and lettuce, respectively, and culture media [tryptic soy agar (TSA) + 50 ppm nalidixic acid (TSAN) for E. coli O157:H7 and Salmonella; TSA for L. monocytogenes). A mixture of cultured test organisms was washed, suspended in phosphate buffer and spot inoculated onto produce or culture media (6 log CFU/sample). Inoculated produce or culture media (samples) were exposed inside a chamber affixed to the …

Prevalence Of Potential Zoonotic Enteric Bacterial Pathogens In Dogs And Cats And Factors Associated With Potential Transmission Between Animals And Humans, Omaima Maamoun Ahmed

Masters Theses

With the discovery of the human immunodeficiency virus (HIV) and acquired immune deficiency syndrome (AIDS), concerns about dangers of pet ownership have increased. Zoonotic organisms associated with cats and dogs, may cause life-threatening infections in immuosuppressed human beings. The objectives of this project were to determine the prevalence of potential zoonotic enteric pathogens (Salmonella, Listeria, and Campylobacter) in feces of dogs and cats (diarrheic, healthy, and hospitalized), to evaluate the association of diarrhea in dogs and cats with diarrhea in human beings sharing the same household, and to evaluate the antimicrobial susceptibility of Salmonella, Listeria …

Molecular Weight And Degree Of Acetylation Of Ultrasonicated Chitosan, Shari Rene Baxter

Masters Theses

Chitosan is a glucosamine polymer produced by deacetylation of chitin from crustacean shells. The functional properties of chitosan, such as thickening, film-formation and antimicrobial activity, are related to its molecular weight and degree of acetylation (DA). High intensity ultrasonication has the potential to modify molecular weight of chitosan and thus alter or improve chitosan functional properties. The objective of this research was to determine the DA and molecular weight of chitosan molecules as a function of sonication intensity and treatment time.

High molecular weight shrimp chitosan was purified by alkaline precipitation and dialysis from aqueous solution. A 1 % (w/v) …

Inactivation Of Escherichia Coli O157:H7 And Listeria Monocytogenes By High-Intensity Ultrasound In The Presence Of Salts, Kimberly D. Stanley

Masters Theses

Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes suspended in salt solutions Na2PO4, NaCl, NaNO3, NH4Cl, CaCl2, AlCl3, and L. monocytogenes in salt solutions NaCl, NaNO3, AlCl3 at concentrations ranging from 0 to 5% (wt/vol) by high-intensity ultrasound at two different temperature conditions (ice water bath, 40ºC water bath) and three ultrasonic intensity levels (9.49, 21.83, 49.22 W/cm2) was determined. Increases in sonication treatment time, intensity and temperature led to increased lethality of both pathogens. However, cell lethality, as a function of solute concentration, varied depending upon type of salt. CaCl2, NaCl, NaNO3, NaPO4, and NH4Cl had little or no …

Production And Characterization Of Fungal Chitin And Chitosan, Tao Wu

Masters Theses

Chitin is a biopolymer. Theoretically, it is a homopolymer of acetyl-glucosamine. Chitosan is the deacetylated product of chitin. Chitin and chitosan have many applications in water purification, agriculture, food and pharmaceutical industries. Currently, industrial production for chitin and chitosan is from the shell wastes. The objective of this study was to evaluate the feasibility of chitin and chitosan production from fungal sources.

The accumulation of chitin and chitosan during A. bisporus storage and Aspergillus niger and Mucor. rouxii. Growth was evaluated by total glucosamine determination. Chitin and chitosan were extracted from biomass by alkali and acid treatment and yield and …

Multistate Study To Determine The Presence Of Salmonella Spp. In Farm Animals And Their Environment, Andres Rodriguez Lozano

Masters Theses

Salmonella is the second most common cause of foodborne infection in the Unites States (US). It is estimated that about 1.4 million people suffer from salmonellosis a year in the US with an estimated annual cost of $2.9 billion. Human cases of salmonellosis are often related to the consumption of raw meat and unpasteurized milk and milk products. Whereas the fecal-oral contamination is well established at farm level, less in known about the role of the environment on the Salmonella survival. The objective of this study was to compare isolation of Salmonella in farm animals and their environment based on …

Volume 2, Number 1 (2004), Ut Institute Of Agriculture

Tennessee Land, Life and Science Magazine

Issue Highlights:

• Emerging Markets
• Value in Good Genes
• Songbirds as Indicators
• Tennessee Agriculture in a Global Market