Food Microbiology Commons^™

Bacterial Expression Of Plant Pyruvate Kinase, Kristina Fuller

STAR Program Research Presentations

Pyruvate kinases serve an important role in regulating glycolysis pathways. Different pyruvate kinase isozymes can dictate which of several different products will be formed during the final step of glycolysis. Being able to reliably copy active pyruvate kinases (PK) would allow study of the different isozymes, with the goal of eventually creating plants that are more nutritionally beneficial for humans. This study focused on improving the protocol for replicating each of two isolated PK isozymes from the model plant Arabidopsis thaliana. Previous attempts had resulted in the PK denaturing and consequently precipitating out of solution and so we manipulated the …

Listeria Monocytogenes'. A Genomic Perspective On Its Pathogenesis, Persistence And Bacteriophages., Aidan Casey

Theses

The objective of this study was to investigate the genetic characteristics of Listeria monocytogenes that contribute to the threat it poses to the food processing industry. Transcriptomic analysis of a persistent L. monocytogenes isolate following exposure to an industrial detergent identified key upregulations in biological processes involved m peptidoglycan biosynthesis, chemotaxis and motility. Two bacteriophages against serotype 4b and 4e isolates of L. monocytogenes were isolated and sequenced. Comparative genomic and functional analysis identified the receptor binding proteins in each phage, whi]e transmission electron microscopy demonstrated a conserved baseplate architecture which also exists in other Gram­positive phages. Comparative genomics of …

Exploiting Bacteriophages And Associated Peptidoglycan Hydrolases With Potential For Biocontrol In Food Related Applications, Lorraine Endersen

Theses

The work presented in this thesis describes the isolation and characterisation of novel bacteriophages, and the subsequent exploitation of their bactericidal properties against two opportunistic food related pathogens, Mycobacterium avium subsp. paratuberculosis (MAP) and Cronobacter sakazakii.

MAP is a proven animal pathogen known to cause Johne’s disease in cattle but has been implicated as a causative agent of Crohn’s disease in humans. Despite the fact that this association has yet to be proven, significant focus has been directed towards evaluating the consequences of consuming milk contaminated with MAP. Accordingly, six mycobacteriophages were isolated and characterised in terms of temperature and …

Acanthamoeba Spp. As Reservoirs For Transmission Of Norovirus, Tun-Yun Hsueh

Graduate Theses and Dissertations

Human noroviruses (HuNoV) are the most common cause of foodborne disease outbreaks in the United States and the most common food commodities implicated in HuNoV outbreaks are leafy greens; however, the vehicle of transmission and point of contamination are often unknown. Here, we hypothesize that common free-living amoebae (FLA) ubiquitous in the environment may act as reservoirs of HuNoV and facilitate the transmission of these pathogens to fresh produce. The objective of this research was to first evaluate the interaction/association between HuNoV surrogates and Acanthamoeba by incubating them together and analyzing virus titer associated with amoeba through an 8 day …

Enhancement Of Antimicrobial Activity Of Naturally Occuring Phenolic Compounds By Nano-Particle Mediated Delivery Against Listeria Monocytogenes, Escherichia Coli O157:H7, And Salmonella Typhimurium, Madhuram Ravichandran

Graduate Theses and Dissertations

Food-borne illnesses are of major concern in the U.S. and worldwide. Salmonella,Listeria,E. coli O157:H7 continue to be some of the major foodborne pathogens. Recurring recalls due to these pathogens demand critical antimicrobial strategies to decontaminate the food through its procession from farm to fork. In our study, we combined the effectiveness of naturally occurring phenolic compounds individually, with/ without ethylenediamine tetraacetic acid (EDTA) and/or Nisin and nanoparticle delivery to improve the antimicrobial potential of the compounds against Listeria monocytogenes (L.m.), Salmonella Typhimurium (S.T.), and Escherichia coli O157:H7 (E.c.), in brain …

The Elimination Of Listeria Monocytogenes Biofilms From Stainless Steel Deli Meat Slicer Components By The Use Of Hurdle Technologies, Alexandria Wynne Mertz

Graduate Theses and Dissertations

Listeria monocytogenes growth is of the greatest concern amongst ready-to-eat foods. The United States Department of Agriculture's Food Safety and Inspection Services determined that deli luncheon meats pose the greatest risk of contamination from L. monocytogenes Industrial meat slicers have many removable parts that are connected with sealers and gaskets, which can become worn over time. These spaces cannot be cleaned adequately, therefore are susceptible to bacterial growth. Planktonic cells form biofilms in order to protect the cell from adverse conditions, like during routine cleaning and sanitation. Once a biofilm is formed, the bacteria are much more difficult to eradicate …

Antibacterial Activity Of Commercially Available Plant Extracts On Selected Campylobacter Jejuni Strains, Divya Oppath Sivasankaran

Graduate Theses and Dissertations

Campylobacter jejuni is recognized as a leading cause of foodborne illness worldwide with approximately 850,000 cases per year in the United Sates. A total of 18 species of Campylobacter have been identified worldwide to date. Foodborne transmission of C. jejuni is mainly through the consumption of unpasteurized milk, contaminated poultry meat and water. C. jejuni can survive in very diverse environments under stressful conditions in human and animals which is different from the specific conditions and media required in laboratory experiments. There has been increased research in recent years to identify naturally occurring antibacterial agents to control and eliminate C. …

Nisin Resistance Of Bacillus Cerus: Preparation Of Nisin, Peter Weber

Journal of Undergraduate Research at Minnesota State University, Mankato

Nisin is a peptide that is made by the bacterium Lactococcus lactis. Nisin is a small molecule that kills gram positive bacteria by binding to their membrane and by disrupting the proton motive force. When food is processed it is heated to kill bacteria, but some bacteria still survive. Adding nisin to the food provides a second barrier for the growth of the bacteria. Purified nisin has become quite expensive in the current marketplace. Therefore this study is directed at producing nisin and purifying it. L. lactis was grown in five different media (BHI, BHI + 1% glucose, BHI + …

Characterization Of Commercial Probiotics: Antibiotic Resistance, Acid And Bile Resistance, And Prebiotic Utilization, Carmen Lucia Cano Roca

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

Probiotics, live microorganisms that beneficially affect the health of their host, must undergo extensive research to ensure they are safe for consumption and possess certain functional properties. Antibiotic resistance in probiotics has raised concern due to the possibility of its transfer to pathogens. Acid and bile tolerance ensures that organisms will survive passage into the intestines. Prebiotic utilization indicates ability to ferment specific carbohydrates for enhanced growth. The objective of this study was to characterize a group of commercial probiotics for their suitability as probiotics.

Nine commercial probiotic strains (7 Lactobacillus, 1 Lactococcus lactis, and 1 Bifidobacterium longum …

Probiotic Potential Of Bacterial Isolates From ‘Amabere Amaruranu’ Cultured Milk, Blaise B. Boyiri

Electronic Theses and Dissertations

Probiotics are viable nonpathogenic microbes that positively affect host health. Probiotics inhibit infection, activate immunity, and promote mucosal-barrier development. Many microbes have probiotic activity. Nonetheless, the selection of stable strains and their specific mechanism(s) of action are not fully elucidated. Bacteria from ‘Amabere amaruranu’ cultured milk from Kenya were isolated and identified by PCR sequence analysis of the 16S rRNA gene. Isolates were examined for stability to acid and bile, antimicrobial activity, mucin production, and degradation and sensitivity to antibiotics, hence their potential for probiotics. Lactobacillus isolates were acid unstable, bile-stable, nonmucinolytic, and presented antibacterial activity. L. rhamnosus cell fractions …

Adherence Inhibition Of Human Pathogens Campylobacter Jejuni And Campylobacter Coli By Non-Digestible Oligosaccharides, Alejandra Ramirez-Hernandez

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

Adherence is the first and one of the most important steps of bacterial pathogenesis. Natural derived components that inhibit the adherence of pathogens to the surface of epithelial cells have received considered interest. The goal of this research was to assess the anti-adherence activity of mannan oligosaccharides (MOS), pectic oligosaccharides (POS) and cranberry high molecular weight component (HMW) against Campylobacter jejuni and Campylobacter coli. First the anti-adherence activity of MOS and their purified fraction (pMOS) was tested against three strains of C. jejuni and two strains of C. coli. Results shown significant reductions in adherence (up to 70%) …

Understanding The Factors Affecting Microbiological Quality Of Wheat Milled Products: From Wheat Fields To Milling Operations, Luis E. Sabillón Galeas

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

Although regarded as a low-risk commodity, wheat flour-based mixes have been implicated in several food safety incidents. The present thesis is a compilation of five scientific manuscripts on the effect of weather variation, milling steps and implementation of pre-milling interventions on the microbiological quality and safety of wheat and milled products. The first manuscript is a review of the microbiological quality and safety of wheat-based products. Despite the low water activity, wheat flour may harbor dormant but viable microorganisms, which could lead to safety concerns when flour is used to produce refrigerated dough products. The second manuscript illustrates the effect …

Non-Digestible Oligosaccharides: Anti-Adherence And Other Biological Properties, Maria I. Quintero-Villegas

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

Bacterial adherence is the first and one of the most important steps in bacterial pathogenesis. Adherence to host cell surfaces requires that the bacteria recognize specific receptors in the surface of epithelial cells. Therefore, agents that act as molecular decoys to interfere with adherence could be useful prophylactic treatments to prevent or mitigate the onset of infections. The goal of this research was to assess the ability of several food grade non-digestible oligosaccharides (NDOs) to act as molecular decoys and prevent bacterial adherence in vitro as well as in vivo. First, the antiadherence effect of specific species chitooligosaccharides (CHOS) …

Traceability Implementation In Organic Farming: Case Study, Chamomile Tea Production, Shaima Abdelfattah Ibrahim

Theses and Dissertations

Implementing a traceability plan in an herbal production plant is a complex task. In this study an attempt to integrate food safety, quality and traceability through the different stages of the organic German Chamomile (Matricaria recutita) production chain was made. First, all the current relevant international laws, regulations and standards regarding traceability, safety and quality, with emphasis on how and why they are necessary for any food production chain, were set forward. Second, physico-chemical and microbiological analyses were run throughout the different processing stages of production, for four different Chamomile batches produced over the same season using the same farming …

Investigating Antibiotic Resistance Levels Of Salmonella Internalized In Lettuce Leaves, Jason B. Thomas

McNair Scholars Research Journal

Contamination of food crops by the human pathogen Salmonella is a food safety threat worldwide. Though using treated wastewater for irrigation is a sustainable practice, it may introduce trace levels of Salmonella that may contaminate food crops. Salmonella could develop resistance to antibiotics present in wastewater. The overall goal of the project is to increase the understanding of the public health risk associated with the use of treated wastewater to irrigate food crops. The objective of this particular study is to determine the antibiotic resistance level of Salmonella internalized in lettuce leaves. In this experiment, thirty-six plants of the lettuce …

Chitosan Reduces Enteric Colonization Of Campylobacter In Young Chickens, But Not On Post-Harvest Chicken Skin Samples, Hanna Royce Arambel

Graduate Theses and Dissertations

Worldwide, Campylobacter is one of the leading causes of foodborne bacterial gastroenteritis causing an estimated 1.3 million infections in the United States alone. Consumption and/or cross-contamination of raw or undercooked poultry products have been linked as the most common source of Campylobacter infection, making the poultry industry a target for Campylobacter reduction strategies. Campylobacter is prevalent in most poultry flocks in the United States, with as many as 90% of flocks Campylobacter-positive at the time of slaughter. It is estimated that a reduction of Campylobacter in poultry would greatly reduce the risk of campylobacteriosis in humans. Unfortunately, there are …

Tracking Heat-Resistant, Sporeforming Bacteria In The Milk Chain: A Farm To Table Approach, Maricarmen Estrada Anzueto

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

Sporeforming bacteria (such as Bacillus and Paenibacillus spp.) can survive pasteurization conditions (Collins, 1981) and grow in pasteurized fluid milk during refrigerated storage (Huck et al., 2008; Ivy et al., 2012), causing fluid milk spoilage and limiting the further extension of fluid milk’s shelf life (Fromm and Boor, 2004; Durak et al., 2006). Moreover, Bacillus and related genera have been found in raw milk, pasteurized milk and environmental samples from dairy farms, indicating that these organisms are ubiquitous in nature and can enter the milk chain from different sources (Huck et al., 2007b; Huck et al., 2008; Ranieri and Boor, …

Debaryomyces Hansenii: A Foodborne Yeast That Produces Anti- Candida Killer Toxin, Nabaraj Banjara

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

Candida yeasts are commensal members of the gastrointestinal, mucosal, oral and vaginal microbiota. Candida albicans and C. tropicalis can be found as a part of the normal human commensal flora, especially in all sections of the gastrointestinal tract. However, when the host defense system and microbiota are disturbed, Candida can become pathogenic and cause severe infection or candidiasis. Antifungal drugs used to treat candidiasis have been shown to result in treatment failures due to drug toxicity and/or development of resistance during long term antifungal therapy and, in recent years, the incidence of Candida infections has increased dramatically due to the …

Transcriptome Analysis Of Listeria Monocytogenes Exposed To Biocide Stress Reveals A Multi-System Response Involving Cell Wall Synthesis, Sugar Uptake, And Motility, Aidan Casey, Edward M. Fox, Stephan Schmitz-Esser, Aidan Coffey, Olivia Mcauliffe, Kieran Jordan

Department of Biological Sciences Publications

Listeria monocytogenes is a virulent food-borne pathogen most often associated with the consumption of “ready-to-eat” foods. The organism is a common contaminant of food processing plants where it may persist for extended periods of time. A commonly used approach for the control of Listeria monocytogenes in the processing environment is the application of biocides such as quaternary ammonium compounds. In this study, the transcriptomic response of a persistent strain of L. monocytogenes (strain 6179) on exposure to a sub-lethal concentration of the quaternary ammonium compound benzethonium chloride (BZT) was assessed. Using RNA-Seq, gene expression levels were quantified by sequencing …

Phages Of Non-Diary Lactococci: Isolation And Characterization Of Phi L47, A Phage Infecting The Grass Isolate Lactococcus Lactis Ssp Cremoris Dpc6860, Daniel Cavanagh, Caitríona M. Guinane, Horst Neve, Aidan Coffey, R. Paul Ross, Gerald F. Fitzgerald, Olivia Mcauliffe

Department of Biological Sciences Publications

Lactococci isolated from non-dairy sources have been found to possess enhanced metabolic activity when compared to dairy strains. These capabilities may be harnessed through the use of these strains as starter or adjunct cultures to produce more diverse flavor profiles in cheese and other dairy products. To understand the interactions between these organisms and the phages that infect them, a number of phages were isolated against lactococcal strains of non-dairy origin. One such phage, ΦL47, was isolated from a sewage sample using the grass isolate L. lactis ssp. cremoris DPC6860 as a host. Visualization of phage virions by transmission electron …

Modelling The Effects Of Natural Antimicrobials As Food Preservatives, Amit Jaiswal, Swarna Jaiswal

Books/Book Chapters/ Proceedings

A predictive food microbiological model is a mathematical representation of mechanisms that describes the growth, survival, inactivation or biochemical process of an organism and are used in the food industry to predict food pathogen growth and to help in the evaluation of food safety. Furthermore, it reduces the number of expensive and time-consuming experiments; however, adequate statistical analysis is a crucial step during all phases of model development and validation. Therefore, the present chapter is focused on the basic concept of mathematical modelling which can be applied to estimate the effects of natural antimicrobials as food preservatives. Initial section discusses …

Atmospheric Cold Plasma Inactivation Of Escherichia Coli, Salmonella Enterica Serovar Typhimurium And Listeria Monocytogenes Inoculated On Fresh Produce, Dana Ziuzina, Sonal Patil, Patrick J. Cullen, Kevin Keener, Paula Bourke

Articles

Atmospheric cold plasma (ACP) represents a potential alternative to traditional methods for non-thermal decontamination of foods. In this study, the antimicrobial efficacy of a novel dielectric barrier discharge ACP device against Escherichia coli, Salmonella enterica Typhimurium and Listeria monocytogenes inoculated on cherry tomatoes and strawberries, was examined. Bacteria were spot inoculated on the produce surface, air dried and sealed inside a rigid polypropylene container. Samples were indirectly exposed (i.e. placed outside plasma discharge) to a high voltage (70kVRMS) air ACP and subsequently stored at room temperature for 24 h. ACP treatment for 10, 60 and 120 s resulted in reduction …

Genome -Scale Reconstruction Of Metabolic Networks Of Lactobacillus Casei Atcc 334 And 12a, Elena Vinay-Lara, Joshua J. Hamilton, Buffy Stahl, Jeff Broadbent, Jennifer L. Reed, James L. Steele

Nutrition, Dietetics, and Food Sciences Faculty Publications

Lactobacillus casei strains are widely used in industry and the utility of this organism in these industrial applications is straindependent. Hence, tools capable of predicting strain specific phenotypes would have utility in the selection of strains forspecific industrial processes. Genome-scale metabolic models can be utilized to better understand genotype-phenotyperelationships and to compare different organisms. To assist in the selection and development of strains with enhancedindustrial utility, genome-scale models for L. casei ATCC 334, a well characterized strain, and strain 12A, a corn silage isolate,were constructed. Draft models were generated from RAST genome annotations using the Model SEED database and refined …

The Effects Of Salinity On Pythium Disease Of Rice And Soybean, Terea Jeanette Stetina

Graduate Theses and Dissertations

Increasing salinity is an important factor limiting agricultural productivity worldwide. In addition to direct effects on growth and yield, diseases also may be affected. This study characterized the effects of soil salinity on seedling disease of soybean and rice caused by Pythium spp. Controlled environment experiments on soybean used two cultivars which differed in chloride tolerance and soil treated with a CaCl₂ solution to create a range of electrical conductivity (EC) levels. For soybean, soil was either not infested or infested with Pythium sylvaticum or P. aphanidermatum (pathogenic to soybean), or P. oligandrum (not pathogenic to soybean). Twenty-one days …

Effect Of Antimicrobials And Sodium Replacement Agents On The Survival Of Pathogenic Bacteria In Low Sodium Low-Moisture Part-Skim (Lmps) Mozzarella Cheese, Tiffany M J Taylor

Master's Theses

Recent increases in chronic cardiovascular diseases, such as hypertension, have put pressure on the food industry to reduce sodium levels. Dairy products, though full of vital nutrients, are perceived as being high in sodium. However, the reduction of salt in dairy products could potentially alter the microbial stability, as well as cause unfavorable changes in flavor. In order to reduce the sodium level, while maintaining acceptable flavor and microbial stability, salt replacers and alternative antimicrobial agents may need to be introduced into the food matrix. To identify potential antimicrobials for use in reduced sodium dairy products, this study evaluated the …

Effect Of Functional Starch In Brown Rice And Grain Sorghum On Plasma Glucose And Insulin Responses In Humans, Nicole Marie Poquette

Graduate Theses and Dissertations

Diabetes and obesity are chronic illnesses increasing at dramatic rates in the U.S. and around the world. Research has looked to prevent or control diabetes and obesity through functional ingredients such as healthy-dietary carbohydrates to control blood glucose levels. Starch is a principle carbohydrate, which influences blood glucose levels, and measuring starch digestibility fractions can help predict the glucose response in the body. The objectives of this study were to investigate the functional starch content of parboiled brown rice flour and grain sorghum flour, and measure the effects on postprandial plasma glucose and insulin levels of 14 and 10 healthy …

Effect Of Electrostatic Spraying Of Food-Grade Organic And Inorganic Acids, And Grape Seed Extract On Salmonella Typhimurium And Escherichia Coli O157:H7 On Spinach And Iceberg Lettuce, Vijayalakshmi Ganesh

Graduate Theses and Dissertations

The safety of fresh produce is often challenged by the sporadic incidences of outbreaks owing to Salmonella Typhimurium (S.T.) and Escherichia coli O157:H7 (E.c.). Washing and current disinfection strategies do not completely decontaminate leafy greens such as spinach and iceberg lettuce. Therefore, more effective treatments are essential to ensure the microbial safety of the produce at the selling point. Here, a multiple hurdle approach was applied: (1) Natural antimicrobials - organic acids (malic, lactic and tartaric acids; MA, LA, TA, respectively) and plant extract (grape seed extract, GSE) and (2) Application method - Electrostatic spraying, was …

Electrostatic Spray Application Of Food-Grade Organic Acids And Plant Extracts To Decrease Escherichia Coli O157:H7 And Salmonella Typhimurium On Select Produce, Leighanna Maeree Massey

Graduate Theses and Dissertations

Both consumers and suppliers have been negatively affected by an increase in foodborne pathogens contaminating fruits. Consequently, there is a need for the development of more efficient antimicrobials and application techniques to decrease contamination. Natural preservatives such as organic acids and plant extracts have demonstrated promising results in decontaminating produce. In addition, the effectiveness of such preservatives may be enhanced by the use of an electrostatic sprayer. The objective of this research was to determine the combinations and concentrations of organic acids and plant extract that were able to reduce Salmonella Typhimurium (ST) and Escherichia coli O157:H7 (EC) inoculated fruits …

Physical And Biochemical Factors Affecting Breast Fillet Tenderness In Broilers Reared For Divergent Market Demands, Valerie Belle Brewer

Graduate Theses and Dissertations

Market trends have dictated that broilers be reared for divergent market demands for decades. Also, broiler genetic strains have been adapted to meet market demands which include: genetic selection for improved breast meat, the practice of growing birds to older ages and greater market weights to meet demands, and decreasing postmortem (PM) aging time to improve processing efficiency and fillet yield. These production practices can also affect product quality, specifically boneless breast fillet tenderness and water-holding capacity. To address these factors, a series of experiments were conducted to determine the effect of strain and slaughter age on meat quality parameters, …

Phenotypic, Physiological And Growth Interactions Among Salmonella Serovars, Juliany Rivera Calo

Graduate Theses and Dissertations

This thesis consists of four research parts: a literature review that covers Salmonella spp., one of the more prominent foodborne pathogens that represents a major risk to humans (chapter 1). Understanding the growth of Salmonella serovars and strains is an important basis for more in depth research. In this case we studied a) the aerobic and anaerobic growth responses of multiple strains from six different serovars, b) how the spent media from different serovars, more importantly S. Heidelberg, affect the growth of S. Typhimurium, and c) determined whether or not two different serovars undergo competitive interactions when they were …