Food Microbiology Commons^™

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 …

2013 Annual Report Of Uvm Extension And The Vermont Agricultural Experiment Station, Uvm Extension And Vermont Agricultural Experiment Station

Annual Reports

2013 Annual report of outreach and research from UVM Extension and Vermont Agricultural Experiment Station.

Probiotics: Finding The Right Regulatory Balance, Diane E. Hoffmann, Claire M. Fraser-Liggett, Frank B. Palumbo, Jacques Ravel, Karen H. Rothenberg, Virginia Rowthorn

Diane Hoffmann

Some products marketed as drugs should be excused from Phase I trials, but safety and efficacy claims for dietary supplements should be more tightly regulated.

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 …

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 …

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 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 …

North Atlantic Vibrio Vulnificus Surveillance From Postharvest Oysters At A Us Shellfish Processing Facility, Kenneth Lavalley, Joseph Dealteris, Michael Rice, Marta Gomez-Chiarri

Marta Gomez-Chiarri

Postharvest surveillance for Vibrio vulnificus by a commercial processing facility was conducted from May 2001 to September 2003. Harvest areas included the Delaware Bay, Long Island Sound and Prince Edward Island. Occurrence followed a seasonal distribution. Low densities were observed in June, increased through August, and became rare by September. Given the ubiquitous nature of marine Vibrios, it was not surprising to find V. vulnificus everywhere, which was investigated. Observations confirmed the importance of strict time/temperature and product handling practices by shellfish harvesters, dealers and processors. Mishandling led to a potentially dangerous and uncharacteristically high V. vulnificus observation.

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 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 …

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 …

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 …

Aqueous Extracts Of Hibiscus Sabdariffa As Antimicrobials In Foods, Kristen Liane Higginbotham

Masters Theses

Hibiscus sabdariffa L. is a tropical shrub species cultivated in multiple countries and is mainly produced for its red calyces that are used for a tea beverage. Aqueous, lyophilized extracts of Hibiscus were examined for their chemical composition and antimicrobial activity against Escherichia coli O157:H7, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), and Listeria monocytogenes.

Lyophilized, dialyzed extracts of commercially aquired calyces were examined in microbiological medium and milk at various fat levels for antimicrobial activity against E. coli O157:H7 and S.aureus. Extracts were either filtered or autoclaved to sterilize and tested in microbiological medium. Autoclaved extracts were more effective …

Antimicrobial Activity Of Essential Oils And Their Components Against Lactic Acid Bacteria, Laurel Dunn Gann

Masters Theses

Efficacy of plant essential oils against spoilage lactic acid bacteria was examined using two different study methods with the goal of determining minimum inhibitory (MIC) and minimum lethal concentrations (MLC) of the essential oils. The initial study included the incorporation of the essential oils, or their major constituents, into agar to allow uniform dispersion of the substance throughout an agar surface. Individual cultures of nine lactic acid bacteria species (Pediococcus acidilactici, Pediococcus damnosus, Lactobacillus fermentum, Lactobacillus fructivorans, Lactobacillus brevis, Lactobacillus buchneri, Lactobacillus plantarum, Leuconostoc mesenteroides, and Leuconostoc citrovorum) were spot …

Inhibition Of Spoilage Yeasts Using Spice Essential Oils And Their Components, Audra Ann Wallis

Masters Theses

Clove bud, cinnamon bark, and thyme oil, along with their components cinnamaldehyde, cinnamic acid, eugenol, carvacrol, and thymol, are widely acknowledged to have antimicrobial properties against bacteria. However, less is know about the inhibitory properties of essential oil components against spoilage yeasts. In this study a minimum inhibitory concentration (MIC) for these essential oils and components was determined using an agar dilution assay for Torulaspora delbrueckii, Candida krusei, Schizosaccharomyces pombe and Zygosaccharomyces bailii. The efficacy of essential oil components eugenol, carvacrol, cinnamaldehyde and thymol then were evaluated in a model salad dressing. The MIC against all yeasts for cinnamaldehyde and …

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, …

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 …

Probiotics: Finding The Right Regulatory Balance, Diane E. Hoffmann, Claire M. Fraser-Liggett, Frank B. Palumbo, Jacques Ravel, Karen H. Rothenberg, Virginia Rowthorn

Faculty Scholarship

Some products marketed as drugs should be excused from Phase I trials, but safety and efficacy claims for dietary supplements should be more tightly regulated.