Life Sciences Commons^™

Detection And Control Of Environmentally Transmissible Viruses, Anand R. Soorneedi

Doctoral Dissertations

Viruses, owing to their ubiquitous nature and ability to infect almost every other species, have long been a subject of interest for scientists. Some of the virus species can be very deadly to humans and animals alike and can impose a huge economic and health burden across the world. The recent CoVID-19 pandemic underscores the importance of timely detection for developing effective intervention strategies. Unfortunately, some of the virus species that cause significant health and economic impacts do not have robust and reliable detection methods due to several reasons. In some cases, despite having gold standard methods for detection of …

Understanding And Developing Safer Sanitation Agents And Strategies In Food Production Environments, Pragathi Kamarasu

Doctoral Dissertations

Food is a primary resource for survival of human beings, and it is also one of the primary resources for spread of infectious diseases. When both these factors come together it does not only cause ill effects on our health but also causes a burden on the food and agricultural industry. Through the help of science, us researchers and scientists have always tried to reduce this burden. And I hope like a drop of water in the ocean in some way my research contributes towards this. According to WHO currently in 2023 there are about 1 in 10 people falling …

Evaluating The Potential Of Ozone Microbubbles For Inactivation Of Tulane Virus, A Human Norovirus Surrogate, Bozhong Guan

Masters Theses

Microbubbles are small gas-filled bubbles with diameters ranging from 50 to 1 μm, and less than 200 nm are called nanobubbles. Their small sizes and large specific surface area result in a high gas dissolution rate and long lifetime in liquid. Ozone is a strong oxidant that destroys microorganisms and only produces oxygen as the final by-product in fresh water. However, due to the poor stability of aqueous ozone, critical gas waste happens during treatments which leads to a high economic loss. Microbubbles have shown promising enhancement of ozone treatment. In previous studies, ozone microbubbles exhibited excellent efficacy in the …

Bifidobacterial Metabolism Of Fucosylated Human Milk Oligosaccharides Influences Structure And Function Of The Infant Gut Microbiome, Liv R. Dedon

Doctoral Dissertations

Human milk contains human milk oligosaccharides (HMOs) that are indigestible and pass intact through the infant gastrointestinal tract where they are available for microbial metabolism. HMOs incorporate the same monosaccharide building blocks but vary structurally in primary sequence of monomeric components. Primary sequences are further diversified by degree of polymerization, branching, and secondary modifications such as fucosylation. Fucosylated HMOs (fHMOs) are highly abundant and can account for over 30% of total HMOs. Infant-colonizing Bifidobacterium longum subsp. infantis (B. infantis) possesses a specialized gene cluster conveying the ability to metabolize fHMOs. This study presents an in-depth analysis of B. …

Enhancement In Photoinactivation Of Food-Borne Pathogenic Bacteria With The Use Of Curcumin And Surfactants, Victor Ryu

Doctoral Dissertations

Photosensitizers and UV or visible light could photoinactivate bacteria. Curcumin was utilized as a food-grade photosensitizer, and an enhancement of its water-dispersibility, chemical stability, and antimicrobial activity when introduced into surfactant solutions was observed. Stock curcumin-surfactant solutions were prepared by titrating curcumin dissolved in ethanol into either Surfynol 465 or Tween 80 solutions (5 mM sodium citrate buffer). Stock curcumin surfactant solutions with different surfactant concentrations were diluted to 1 µM prior to irradiation. The resulting solutions also had surfactant concentrations below, near, and above their critical micelle concentrations (CMCs) of the respective surfactants. The antimicrobial activity of the curcumin-loaded …

Detection Of Mycotoxins Using Surface-Enhanced Raman Spectroscopy, Lourdes B. Martinez Rojas

Doctoral Dissertations

Mycotoxins are toxic metabolites produced by fungus that can be parasites or saprophytes of crops or livestock forage. Consumer demand for plant-based foods and interest in animal-based foods originating from animals fed plant-based feed has been on the rise. Therefore, monitoring mycotoxins occurring in the food supply is more critical than ever. The goal of this project is to improve surface-enhanced Raman spectroscopy’s (SERS) ability to identify and detect mycotoxins using label-free SERS substrates. Two simple approaches were designed to enhance the detection of mycotoxins produced by the Aspergillus and Penicillium genera, ochratoxin A and aflatoxin B1. Ochratoxin A was …

Antibiotic Sensitivity Testing Of Foodborne Bacteria Using Surface-Enhanced Raman Spectroscopy, Joshua Gukowsky

Doctoral Dissertations

The spread of antibiotic resistant bacteria around the world has become a major public health issue, and it is essential that effective detection methods exist for identifying these organisms and preventing them from spreading throughout our food systems and into the environment. The goal of this research is to develop a novel analytical procedure that is capable of easily identifying antibiotic resistance in bacterial samples, and also provides more information about the biochemical characteristics of the bacteria and their responses to antibiotic exposure. Surface-enhanced Raman Spectroscopy (SERS), an analytical technique that uses light scattering to produce a spectrum based on …

Effects Of Tempeh Fermentation On Soy Free And Bound Phenolics: Release, Transformation, And Stimulated Production, Amadeus Driando Ahnan

Doctoral Dissertations

The fermentation of tempeh, a traditional source of protein originated in Indonesia, has been reported to enhance the health-promoting potentials of various grains, legumes, and beans. Tempeh fermentation on soybeans can modulate the bioavailability of phenolic compounds, particularly isoflavones, bioactive compounds that have been found to be protective against lung, prostrate, and colon cancers. However, the mechanism of the protective benefits was unknown. Using whole-food and in vitro models, this study addressed this research gap by investigating the effects of tempeh fermentation using various cultures on the compositions of soy free, bound, and minor phenolics, as well as their antioxidative, …

Micro-Physiological Models To Mimic Mucosal Barrier Complexity Of The Human Intestine In Vitro, Abhinav Sharma

Doctoral Dissertations

The mucosal barrier in the intestine is vital to maintain selective absorption of nutrients while protecting internal tissues and maintaining symbiotic relationship with luminal microbiota. This bio-barrier consists of a cellular epithelial barrier and an acellular mucus barrier. Secreted mucus regulates barrier function via in situ biochemical and biophysical interaction with luminal content that continually evolves during digestion and absorption. Increasing evidence suggests that a mucus barrier is indispensable to maintain homeostasis in the gastrointestinal tract. However, the importance of mucus barrier is largely underrated for in vitro mucosal tissue modeling. The major gap is the lack of experimental material …

Dietary Oligosaccharides Modulate Bifidobacterial Production Of The Neurotransmitter Gamma-Aminobutyric Acid, Michelle Rozycki

Masters Theses

Bifidobacteria are the predominant members of the infant gut, colonize adults to a lesser extent, and are recognized as beneficial microbes. Various bifidobacterial species produce ��-aminobutryic acid (GABA), the chief inhibitory neurotransmitter in the mammalian central nervous system. It is postulated that in order to produce GABA, the bifidobacterial genome must contain the gadB and gadC genes which encode a glutamate decarboxylase and a glutamate/GABA antiporter, respectively. Once exported by GadC, GABA is absorbed and transported systemically throughout the host. We hypothesize that specific dietary oligosaccharides will modulate bifidobacterial production of GABA due to varying intracellular concentrations of glutamate. To …

Development Of Headspace Analysis Of Living And Postharvest Fresh Produce Using Surface-Enhanced Raman Spectroscopy (Sers), Xinyi Du

Masters Theses

The increasing market demand for fresh produce promotes a keen interest in developing a rapid, sensitive and reliable method for monitoring plant health and determining the shelf-life of postharvest produce. The objective of this study is to explore the capability of Surface-enhanced Raman spectroscopy (SERS) in these applications. SERS integrates Raman spectroscopy which measures molecular vibrations and nanotechnology which enhances the weak Raman signals. Herein, we developed two SERS methods based on a surface detection approach using nanoparticles solution and a headspace detection approach using gold nanoparticles (AuNPs) fibers, to detect biochemical changes during postharvest storage of arugula leaves. Compared …

Utilization Of Emulsion Chemistries For Delivery And Antiviral Application Of Carvacrol, Hao-Yuan Hsu

Masters Theses

Human norovirus (HuNoVs) are the most common enteric pathogen around the world that cause ~50% of foodborne illness of disease outbreaks annually. HuNoVs are the member of the Caliciviridae family, which consist of small (38 nm), unenveloped, single stranded RNA (ssRNA) viruses. Norovirus are divided into 5 genogroup (GI, GII, GIII, GIV, GV, GVI and GVII). The GI, GII, and GIV cause human illness, in addition, GII.4 genotype cause the most human disease. Due to HuNoVs are difficult cultured in vitro, the cultivable HuNoVs surrogates have been widely studied. Recently, some studies have been conducted with HuNoVs surrogates, for …

Promotion Of Colon Health By Strawberry And Cranberry, Yanhui Han

Doctoral Dissertations

Inflammatory bowel disease (IBD) has posed serious threats to the human health, which lead to chronic malabsorption of nutrients, abnormal pain and rectal bleeding. Both genetic predisposition and environmental factors contribute to the onset of IBD. Multiple studies suggested that dysbiosis in colon plays an important role in the development of colitis, and gut microbiota composition are different between patients with IBD and healthy individuals. Intake of whole foods, such as fruits and vegetables, may confer health benefits to the host. The beneficial effects of fruits and vegetables mainly attribute to their richness of polyphenols and microbiota-accessible carbohydrates (MACs). Components …

The Catalytic Urease Subunit Urec Is Critical For Bifidobacterium Longum Urea Utilization, Yang Lyu

Doctoral Dissertations

In the first study, we investigated the utilization of a human milk nitrogen source, urea, by Bifidobacterium. Urea accounts for ~15% in human milk, which is an abundant non-protein nitrogen (NPN). Some bifidobacteria are found to harbor urease gene clusters that potentially enable their hydrolysis of the human milk urea. However, the underlying mechanisms are still unclear. To incisively link the urease gene cluster with bifidobacterial urea utilization, chemical mutagenesis (i.e. ethyl methanesulfonate) was performed on the urease-positive Bifidobacterium longum subsp. suis UMA399. Mutants were selected on differential media and genetic lesions were identified using whole genome sequencing. …

Dietary Oligosaccharides Are Differentially Metabolized By Commensal Microbiota Within In Vitro Model Systems, Ezgi Özcan

Doctoral Dissertations

Our diet contains indigestible carbohydrates that are available for microbial metabolism within the gastrointestinal tract. These carbohydrate sources are oligosaccharides found in plants and human milk. Oligosaccharide utilization phenotypes are often consistent with the ecological niche that microbes occupy (e.g. adult gut, infant gut, plants). This study represents an in-depth metabolic analysis for utilization of human milk oligosaccharides (HMOs) including lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT), and cranberry oligosaccharides (i.e. xyloglucans) within in vitro modeled systems. These model systems include microplate systems for pure cultures as well as an adapted bioreactor system to mimic microbial interactions within the gut. Infant-colonizing Bifidobacterium …

The Efficacy Of Atp Monitoring Devices At Measuring Organic Matter On Postharvest Surfaces, Kristin Lane

Masters Theses

The Food Safety Modernization Act (FSMA), specifically the Produce Safety Rule (PSR), requires growers to clean and sanitize food-contact surfaces to protect against produce contamination. The ATP monitoring device is a potential sanitation tool to monitor the efficacy of an on-farm cleaning and sanitation program that could help growers meet regulatory expectations mandated by PSR. The ATP device uses bioluminescence to detect all ATP (found in bacteria and produce matter cells) from a swabbed surface. Little work has been done to test the efficacy of these tools under postharvest conditions. The present study evaluated ATP measurement for postharvest surface cleanliness …

Influence Of Shipping Container Upon Temperature, Relative Humidity, And Bacterial Growth On Broccoli, Nicholas Berus

Masters Theses

Temperature and relative humidity of produce throughout the cold chain can greatly affect the quality and safety of the food product. Different packaging systems or containers can provide better cooling environments for food products that could decrease temperature abuse and ultimately safety risks. In this study we compiled temperature and relative humidity profiles of broccoli packed in different shipping containers throughout the produce supply chain. The shipping containers looked at were the wax corrugated box, reusable plastic containers (RPC), and Eco Pack Green Box with and without a lid. Large differences were seen in the temperature profiles of each package …

Biotransformation Of Resveratrol And Its Implications In Biological Activities In The Colon, Fang Li

Doctoral Dissertations

Resveratrol (RES) is a natural polyphenol compound with a wide range of health-promoting activities, including protective effects against colon cancer and renal disease. However, the premise of these benefits has been dampened since RES shows a poor oral bioavailability due to its rapid and extensive biotransformation after oral consumption. The paradox (low bioavailability but high bioactivity) warrants further investigations to determine the contribution of RES metabolites to the health benefits associated with RES. We identified 11 metabolites of RES in mice with high-resolution HPLC-MS/MS, then quantified two major metabolites - dihydro-resveratrol (DHR) and lunularin (LUN). To further understand the chemopreventative …

Use Of Alamarblue As An Indicator Of Microbial Growth In Turbid Solutions For Antimicrobial Evaluation, Precious Henshaw

Masters Theses

The use of antibiotics in animal feed is a large cause of concern due to bacterial resistance, which occurs when bacteria change after exposure to antibiotics and become less affected by the drug. Consequently, the desire to find a replacement for these antibiotics has garnered interest in both farmers and consumers. The ideal substance would display antimicrobial activity without promoting bacterial resistance and would still function as a growth promoter in animals. One antimicrobial that fits this criterion is carvacrol, a compound found in oregano extract. Carvacrol exhibits antimicrobial activity in a number of bacteria, including E.coli O157:H7 and S. …

Screening Of Commercially Available Chlorine Based Sanitizers And Their Efficacy In Reducing Microbial Load Levels Of E. Coli O157:H7 At High And Low Organic Load Environments, Paola Martinez-Ramos

Masters Theses

The presence of postharvest sanitizers has shown to be an effective approach to reducing microbial cross contamination in agricultural washing operations. However, choosing an appropriate sanitizer can be challenging due to produce commodity, processing conditions and interference with organic load. Current research shows a wide variety of methods to mimic the organic load of vegetable processing conditions, with paddle mixing and blender as the most commonly used. Controlling and understanding the physiochemical properties of wash water is key in maintaining sanitizer efficacy. The effects of simulated wash water preparation method on the physiochemical properties were tested at 0 and 50 …

Optimization Of Peracetic Acid As An Antimicrobial Agent In Postharvest Processing Wash Water, Tiah Ghostlaw

Masters Theses

The Food Safety Modernization Act (FSMA) has a regulation stating that there can be no detectable generic Escherichia coli in agricultural water. The objective of this study was to optimize the use of peracetic acid (PAA) as a mitigating strategy in postharvest processing. This project began by investigating the impact of storage temperatures on stability of a commercially available PAA sanitizer. Regression analysis showed a quadratic relationship in the concentration of PAA over 12 weeks when storing the product at 4, 20 and 37°C. Stability of the product was also investigated in the presence of organic load over time at …

Development Of Methodology For Rapid Bacterial Detection In Complex Matrices Using Sers, Madeline Tucker

Masters Theses

Fresh foods, including meats and produce are the fastest growing market in the supermarket and the class of foods most likely to cause a bacterial foodborne illness. As the rate of consumption of perishable products increases, rapid detection of pathogens within the food supply becomes a critical issue. Current methods used for the detection of bacteria that cause food-borne illnesses are time consuming, expensive and often require selective enrichment. In this study we adapted a separation technique originally developed for PCR to extract bacteria from ground beef using β-cyclodextrin (β-CD) and milk protein coated activated carbon (MP-CAC) as filtration agents. …

Caenorhabditis Elegans Model To Study Antimicrobial Treatment On E. Coli O157:H7, Parita Patel

Masters Theses

An increase in antimicrobial resistance bacteria has endangered our ability to treat infectious diseases. Lack of good in-vivo model has made it difficult to study antimicrobial resistance. In this study, we have used an inexpensive and short life span in-vivo model namely, Caenorhabditis elegans (C. elegans) to study antimicrobial treatment using pathogenic Escherichia coli O157:H7, a multidrug resistance bacterium that causes life threatening infection in humans.

We have investigated the influence of live vs. heat killed non-pathogenic E. coli OP50 (OP50) as a food source on the growth and survival of infected C. elegans mutant AU37 with E. …

Use Of Different Ripening Inhibitors To Enhance Antimicrobial Activity Of Essential Oil Nanoemulsion, Victor Ryu

Masters Theses

The objective of this research was to study the impact of ripening inhibitor level and type on the formation, stability, and activity of antimicrobial thyme oil nanoemulsions formed by spontaneous emulsification. Oil-in-water antimicrobial nanoemulsions (10 wt%) were formed by titrating a mixture of essential oil, ripening inhibitor, and surfactant (Tween 80) into 5mM sodium citrate buffer (pH 3.5). Stable nanoemulsions containing small droplets (d < 70 nm) were formed. The antimicrobial activity of the nanoemulsions decreased with increasing ripening inhibitor concentration, which was attributed to a reduction in the amount of hydrophobic antimicrobial constituents transferred to the separated hydrophobic domain, mimicking bacterial cell membranes, by using dialysis and chromatography. The antimicrobial activity of the nanoemulsions also depended on the nature of the ripening inhibitor used: palm ≈ corn > canola > coconut which also depended on their ability to transfer hydrophobic antimicrobial constituents to the separated hydrophobic domain.

Influence Of Biomimetic Chelating Packaging On Natural Antimicrobial Efficacy, Paul Castrale

Masters Theses

The iron chelating molecule, ethylenediaminetetraacetic acid (EDTA) is used in food applications for the preservation of oxidation prone ingredients. Research has suggested that EDTA is also capable of enhancing the antimicrobial effectiveness of various compounds including naturally-derived antimicrobials. With consumer demand for cleaner food labels, there remains an opportunity to introduce new chelating technology to replace synthetically-derived EDTA. Through photographting and chemical conversion, hydroxamic acid ligands were covalently bound to polypropylene films resulting in polypropylene-graft-poly(hydroxamic acid) (PP-g-PHA). The resulting films demonstrated an ability to chelate 64 nmol/cm² from an iron saturated environment or 163 nmol/cm …

Investigating Natural And Induced Biofilm Dispersion In Listeria Monocytogenes, Brett Boulden

Masters Theses

Dispersion is a natural part of a biofilm life cycle in many bacterial species. Dispersion occurs when bacteria revert from a stationary, sessile state to a free-swimming, planktonic state and are freed from a biofilm. Bacterial biofilms consist of proteins, polysaccharides, and extracellular DNA that together make up the extracellular polymeric substances. Surrounded by this mucus-like substance, sessile cells can be extremely difficult to eradicate as compared to the planktonic form of Listeria monocytogenes. Biofilms are robust due to increased surface adherence, inhibition of diffusion of harmful compounds, and increased genetic diversity that exists within a biofilm. As a …

Epigallocatechin-3-Gallate Reduces Fat Accumulation In Caenorhabditis Elegans, Jinning Liu

Masters Theses

Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is a polyphenol that is most abundant in tea. It has been shown from many studies that consumption of EGCG can contribute to weight loss, however, the underlying mechanism is not fully understood. To determine how EGCG acts to reduce fat, an organism model Caenorhabditis elegans (C. elegans) is introduced, which is a useful animal system in exploring crucial biological mechanisms that are readily applicable to humans. In this study, different strains were raised for two days on a diet with or without 100µM and 200µM EGCG treatment: N2 (i.e., wild …

Biopolymer Electrospun Nanofiber Mats To Inactivate And Remove Bacteria, Katrina Ann Rieger

Doctoral Dissertations

The persistence of antibiotic resistance in bacterial pathogens remains a primary concern for immunocompromised and critically-ill hospital patients. Hospital associated infections can be deadly and reduce the successes of medical advancements, such as, cancer therapies and medical implants. Thus, it is imperative to develop materials that can (i) deliver new antibiotics with accuracy, as well as (ii) uptake pathogenic microbes. In this work, we will demonstrate that electrospun nanofiber mats offer a promising platform for both of these objectives because of their high surface-to-volume ratio, interconnected high porosity, gas permeability, and ability to contour to virtually any surface. To provide …

Label-Free And Aptamer-Based Surface Enhanced Raman Spectroscopy For Detection Of Food Contaminants, Shintaro Pang

Doctoral Dissertations

The development of analytical methods to detect food contaminants is a critical step for improving food safety. Surface enhanced Raman spectroscopy (SERS) is an emerging detection technology that has the potential to rapidly, accurately and sensitively detect a wide variety of food contaminants. However, SERS detection becomes a challenge in real complex matrix, such as food, since non-specific matrix signals have the potential to drown out target associated Raman peaks. In this dissertation, we focused on the development and application of label-free, aptamer-based SERS in order to improve the accuracy and specificity of target contaminant detection in food. To accomplish …

Bacteriophage-Based Colorimetric Detection Of Escherichia Coli In Drinking Water, Juhong Chen

Doctoral Dissertations

One of the major safety causes in drinking water is from the bacteria contamination, especially in developing countries and resource-limited settings. Although many of these Escherichia coli (E. coli) strains in drinking water are nonpathogenic, they sever as the indicator for bacterial contamination. And, the more widely used method to detect E. coli in drinking water is to determine the activity of β-galactosidase (β-gal), which is released by E. coli. Rapid, sensitive and inexpensive detection of E. coli in drinking water can reduce the risk of food-borne bacteria infection and stop the disease widely spreading. In this …