Food Microbiology Commons^™

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 …

Radiofrequency Processing For Inactivation Of Salmonella Spp. And Enterococcus Faecium Nrrl B-2354 In Whole Black Peppercorn And Ground Black Pepper, Xinyao Wei

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

Black pepper has been implicated in several foodborne illness outbreaks and food product recalls due to Salmonella contamination. Conventional decontamination methods for black pepper are challenged by harmful residues or quality deterioration. Radiofrequency (RF) heating reduces the come-up time which allows to design a high-temperature short-time processing to inactivate Salmonella with minimal deterioration in product quality. The objectives of this study were to investigate RF heating for inactivation of Salmonella in whole black peppercorn and ground black pepper samples, evaluate Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella, and assess quality deterioration during RF heating of whole black peppercorn …

Validation Of Extrusion Processing For The Safety Of Low-Moisture Foods, Tushar Verma

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

Salmonella in low-moisture foods is an emerging challenge due to numerous food product recalls and foodborne illness outbreaks. The new Food Safety Modernization Act requires the food processors to validate their process controls that indeed kills the desired number of bacteria. This research had two major objectives: 1) Develop a response surface model for Salmonella inactivation during the extrusion of low-moisture food 2) Evaluate the use of Enterococcus faecium NRRL B-2354 as an adequate surrogate for Salmonella during the extrusion of low-moisture food. Oat flour was selected as a low-moisture food model. For inoculation, cocktail of five different strains of …

Modeling The Survival Of Salmonella In Soy Sauce-Based Products Stored At Two Different Temperatures, Ana Cristina Arciniega Castillo

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

Acidified foods are defined in the regulations as “low acid foods to which acid(s) has been added to bring finished pH to 4.6 or below”. As the market for these products expands, an increasing number of them are being processed with reduced heat treatment, relying on acid alone to ensure the destruction of pathogens. When considering the survival rate of microbial pathogens in these products, pH, water activity, temperature, salt content and holding time are integral and must be considered together.

Despite improvements in production, handling, and distribution of food products in recent years, protecting consumers from foodborne illness still …

Growing Yeast For Livestock, Zachary Christman

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

Over 500,000 tons of organic materials such as food scraps are disposed of each year in Wisconsin. A large percentage of this material could be composted or turned into useful products. The purpose of this article is to educate farmers and organizations on how to turn food waste into a high value food source for livestock. Yeast can be grown at any time of the year without the large inputs of agricultural chemicals and machinery that is common with other feed production methods. A yeast growing facility can be scalable to any size the producer wants such as a small …

A Critical Assessment Of The “Sterile Womb” And “In Utero Colonization” Hypotheses: Implications For Research On The Pioneer Infant Microbiome, Maria Elisa Perez-Muñoz, Marie-Claire Arrieta, Amanda E. Ramer-Tait, Jens Walter

Department of Food Science and Technology: Faculty Publications

After more than a century of active research, the notion that the human fetal environment is sterile and that the neonate’s microbiome is acquired during and after birth was an accepted dogma. However, recent studies using molecular techniques suggest bacterial communities in the placenta, amniotic fluid, and meconium from healthy pregnancies. These findings have led many scientists to challenge the “sterile womb paradigm” and propose that microbiome acquisition instead begins in utero, an idea that would fundamentally change our understanding of gut microbiota acquisition and its role in human development. In this review, we provide a critical assessment of the …

Risk Assessment And Research Synthesis Methodologies In Food Safety: Two Effective Tools To Provide Scientific Evidence Into The Decision Making Process, Juan E. Ortuzar

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

The food supply chain is a complex and diverse system. Some food products need minimum processing to reach the consumers, while others involve several different processes, countries and suppliers, can take several months to be on the table of the end consumer. Regarding food safety, the public health of consumers is at stake and the consequences of outbreaks could prove disastrous. This has been recognized as a matter of global importance for the food industry and authorities around the world since several efforts to improve quality, safety and trade of food have arisen since the early 1960s. The birth of …

Stable Engraftment Of Bifidobacterium Longum Ah1206 In The Human Gut Depends On Individualized Features Of The Resident Microbiome, María X. Maldonado-Gómez, Inés Martínez, Francesca Bottacini, Amy O’Callaghan, Marco Ventura, Douwe Van Sinderen, Benjamin Hillmann, Pajau Vangay, Dan Knights, Robert W. Hutkins, Jens Walter

Department of Food Science and Technology: Faculty Publications

Live bacteria (such as probiotics) have long been used to modulate gut microbiota and human physiology, but their colonization is mostly transient. Conceptual understanding of the ecological principles as they apply to exogenously introduced microbes in gut ecosystems is lacking. We find that, when orally administered to humans, Bifidobacterium longum AH1206 stably persists in the gut of 30% of individuals for at least 6 months without causing gastrointestinal symptoms or impacting the composition of the resident gut microbiota. AH1206 engraftment was associated with low abundance of resident B. longum and underrepresentation of specific carbohydrate utilization genes in the pre-treatment microbiome. …

Fungi In The Healthy Human Gastrointestinal Tract, Heather E. Hallen-Adams, Mallory J. Suhr

Department of Food Science and Technology: Faculty Publications

Many species of fungi have been detected in the healthy human gut; however, nearly half of all taxa reported have only been found in one sample or one study. Fungi capable of growing in and colonizing the gut are limited to a small number of species, mostly Candida yeasts and yeasts in the family Dipodascaceae (Galactomyces, Geotrichum, Saprochaete). Malassezia and the filamentous fungus Cladosporium are potential colonizers; more work is needed to clarify their role. Other commonly-detected fungi come from the diet or environment but either cannot or do not colonize (Penicillium and Debaryomyces species, which are …

From Milpas To The Market: A Study On The Use Of Metal Silos For Safer And Better Storage Of Guatemalan Maize, José Rodrigo Mendoza

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

This project aimed to implement the use of metal silos to improve quality and safety of maize consumed by inhabitants of the highlands of Guatemala. This manuscript includes a literature review of the maize production chain in Guatemala, a survey about agricultural practices used in the region of study, as well as a characterization of the analyzed maize regarding its mycoflora, nutritional composition, and insect infestation. To better understand the current situation regarding agricultural practices and maize consumption, a survey was carried out. Sample consisted of 280 families representing 14 rural communities distributed in the townships of Todos Santos and …

The Effect Of Salt Reduction On The Microbial Composition And Quality Characteristics Of Sliced Roast Beef And Turkey, Chad Gary Bower

Department of Animal Science: Dissertations, Theses, and Student Research

This study analyzed the effects of salt reduction on microbiological composition and quality characteristics of deli-style turkey breast and roast beef. Turkey breast and roast beef were manufactured with four different salt concentrations: 1.0%, 1.5%, 2.0%, and 2.5% on a meat block basis in addition to sugar, phosphate, and water. Samples were cooked, chilled overnight, sliced, and packaged. On the day of slicing, samples were evaluated for water activity, cooking yield, proximate composition and percent salt. Samples were evaluated throughout 18w of refrigerated storage for pH, texture profile analysis, aerobic plate count (APC), and anaerobic plate count. Bacterial communities were …

Synbiotic Ice Cream As A Probiotic Carrier Tested In A Human Blind Crossover Trial, Erin M. Mcnamara

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Diet is an important factor in gastrointestinal health. A synbiotic food option utilizing prebiotic and probiotic ingredients may be beneficial for improving gastrointestinal health. To conduct a human subject study of synbiotic ice cream containing prebiotic (inulin) and two strains of probiotics (Lactobacillus casei KE99 and Bifidobacterium bifidum) to determine its effectiveness as a carrier for a these ingredients and to identify any negative gastrointestinal side effects.

The study started with baseline data collection including a food frequency, a three day food recall, and one stool sample. The study was a 12 week crossover design with three weeks consuming …

Studies Of Debaryomyces Hansenii Killer Toxin And Its Effect On Pathogenic Bloodstream Candida Isolates, Rhaisa A. Crespo Ramírez

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

Candida species are normal commensal organisms found in the skin, mouth, and gastrointestinal and genitourinary tracts of humans. Candida albicans is a normal component of the gut flora, and the oral and genital cavities. However, this organism is an opportunistic pathogen and it is one of the most frequently isolated species from patients with nosocomial fungal infections. Candida infections have grown in recent years due to antimycotics resistance and the extensive use of antibiotics. This has pushed scientists to look for alternative therapeutic agents to treat fungal infections.

Yeasts can produce toxic proteins called “mycocins” or “killer toxins” that can …

Antibacterial Effects Of Peppermint, Mentha Piperita Essential Oil In Free-Form And In Nanoparticles On Pseudomonas Fluorescens, Car Reen Kok, Junsi Yang, Ozan Ciftci, Robert W. Hutkins

UCARE: Research Products

Mentha piperita, commonly known as peppermint originally came from Europe and the Middle East and its oil is commonly used in traditional medicine and aromatherapy. Like many other free essential oils (EO), peppermint oil is believed to possess antimicrobial properties.

However, the application of EO in food as an antimicrobial agent has yet to be established. This would require proper formulation of the EO for it to be viable in foods. This study aims to test the effects of both free Mentha piperita EO and Mentha piperita EO nanoparticles against Pseudomonas fluorescens and compare their inhibitory effects. We used nanoparticles …

Prebiotics And Synbiotics: Dietary Strategies For Improving Gut Health, Janina A. Krumbeck, Maria X. Maldonado-Gomez, Amanda E. Ramer-Tait, Robert W. Hutkins

Department of Food Science and Technology: Faculty Publications

Purpose of review — A wide range of dietary carbohydrates, including prebiotic food ingredients, fermentable fibers, and milk oligosaccharides, are able to produce significant changes in the intestinal microbiota. These shifts in the microbial community are often characterized by increased levels of bifidobacteria and lactobacilli. More recent studies have revealed that species of Faecalibacterium, Akkermansia, and other less well studied members may also be enriched. We review the implications of these recent studies on future design of prebiotics and synbiotics to promote gastrointestinal health.

Recent findings — Investigations assessing the clinical outcomes associated with dietary modification of the …

Comparative Study Of The D-Values Of Salmonella Spp. And Enterococcus Faecium In Wheat Flour, Didier Dodier

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

Low-moisture foods contaminated with Salmonella spp. have been implicated in several foodborne illness outbreaks in the United States. The food industry has to incorporate preventive control in their process and validate thermal processes to assure food safety. The thermal destruction of Enterococcus faecium ATTC 8459 and Salmonella spp. was determined at 3 water activity levels (0.11, 0.18 and 0.33) at 80ºC, 85ºC and 90ºC. Aerobic plates counts petrifilms were used as non-selective medium for both bacteria, Enterobacteriaceae petrifilms were used as selective medium for Salmonella spp., and peptone water modified with sodium azide as a selective medium for Enterococcus faecium …

Inactivation Of Escherichia Coli O157:H7 And Shiga Toxin Producing E. Coli (Stec) Throughout Beef Summer Sausage Production And The Use Of High Pressure Processing As An Alternative Intervention To Thermal Processing, Eric L. Oliver

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

Escherichia coli O157:H7 and six additional serogroups of Shiga Toxin-producing E. coli (STEC-7) have been implicated in foodborne illness outbreaks related to fermented sausage products and are considered adulterants by the USDA-FSIS. The objective of this study was to evaluate high pressure processing (HPP) as an alternative to thermal treatment to reduce STEC-7 meeting the USDA-FSIS performance standards (5.0-log reduction). A rifampicin-resistant, non-pathogenic E. coli (surrogate) cocktail, was used in manufacturing testing. Sausages were fermented at ~42.2°C, slowly increased to 54.4°C internal temperature, cold showered, and chilled for 6 hours. Sampling occurred post-fermentation (PF; pH 5.0), internal temperature 48.9°C (I-48.9°C), …

Efficacy Of Galactooliosaccharide (Gos) And/Or Rhamnose-Based Synbiotics In Enhancing Ecological Performance Of Lactobacillus Reuteri In The Human Gut And Characterization Of Its Gos Metabolic System, Monchaya Rattanaprasert

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

Probiotic L. reuteri has potential to produce antimicrobial compounds and secrete immunosuppressive factors. These metabolic attributes could benefit the human host by providing colonization resistance (competitive and metabolic exclusion) against enteropathogens and mitigating inflammation. As metabolically active cells are fundamental to such probiotic properties, synbiotic approaches that supply L. reuteri with a source(s) of carbon, energy, and/or external electron acceptor for cell growth in the gut environment could therefore prompt the probiotic to engage in beneficial activities. In this study, the efficacy of GOS and/or rhamnose-based synbiotic approaches in promoting colonization persistence and metabolic activity of L. reuteri was evaluated. …

Dietary Microrna Database (Dmd): An Archive Database And Analytic Tool For Food-Borne Micrornas, Kevin Chiang, Jiang Shu, Janos Zempleni, Juan Cui

School of Computing: Faculty Publications

With the advent of high throughput technology, a huge amount of microRNA information has been added to the growing body of knowledge for non-coding RNAs. Here we present the Dietary MicroRNA Databases (DMD), the first repository for archiving and analyzing the published and novel microRNAs discovered in dietary resources. Currently there are fifteen types of dietary species, such as apple, grape, cow milk, and cow fat, included in the database originating from 9 plant and 5 animal species. Annotation for each entry, a mature microRNA indexed as DM0000*, covers information of the mature sequences, genome locations, hairpin structures of parental …

Viability Of Lactobacillus Acidophilus Dds 1-10 Encapsulated With An Alginate-Starch Matrix, Liya Mo

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

L. acidophilus DDS1-10 was encapsulated using an alginate, potato starch and type 4 resistant starch (RS4) matrix. The wall material was optimized by varying levels of alginate (1.6 to 4.4%), while maintaining potato starch and RS4 ratio fixed at 2, and the total solid content at 5%. Particles were prepared using an emulsion and an extrusion method. Particles obtained from the emulsion method were smaller with a non-uniform distribution in size while those obtained by the extrusion method were bigger and uniform in size. The emulsion method did not seem to offer protection to the probiotic cells against pH, bile …

Characterization And Investigation Of Fungi Inhabiting The Gastrointestinal Tract Of Healthy And Diseased Humans, Mallory J. Suhr

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

Gastrointestinal microbiome studies have failed to include fungi in total community analyses. As a result, their diversity and function in the gut is poorly understood. Recent work has begun to uncover the role intestinal fungi play in diet, immune system development, interactions with other microorganisms in the gut, and pathogenesis of diseases. Advances in sequencing technologies allow for the ability to profile the fungal gut microbiome (“mycobiome”) in healthy and diseased states. This thesis explores the mycobiome in 1) healthy humans with a vegetarian diet and 2) pediatric small bowel transplant recipients that develop fungal bloodstream infections.

The gut mycobiome …

The Influence Of The Bovine Fecal Microbiota On The Shedding Of Shiga Toxin-Producing Escherichia Coli (Stec) By Beef Cattle, Nirosh D. Aluthge

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

During the past three decades, Shiga toxin-producing E.coli (STEC) have emerged as an important food safety concern. Although initially E. coli O157 was the main focus, recent outbreaks and resulting investigations have shown that certain non-O157 STEC are as much a threat to food safety as their O157 counterparts. To the beef industry, STEC have been of particular concern due to the frequent association of beef and beef products as vehicles of STEC infection. As a result, along with E. coli O157, six non-O157 STEC serogroups (known as the ‘big six’) are now regulated as adulterants in certain raw beef …

Micrornas Are Absorbed In Biologically Meaningful Amounts From Nutritionally Relevant Doses Of Cow’S Milk And Chicken Eggs And Affect Gene Expression In Peripheral Blood Mononuclear Cells, Cell Cultures, And Mouse Livers, Scott Baier

Department of Nutrition and Health Sciences: Dissertations, Theses, and Student Research

Throughout the twenty-first century, evidence has been continually increasing to show the importance of epigenetic regulation in health. While the term “epigenetics” can be applied to many different processes, the focus of this dissertation will be on microRNAs and chromatin structure. Ultimately, both of these forms of epigenetic regulation can be used to fine tune gene expression based on environmental cues. The first three chapters of the dissertation focus on microRNA bioavailability, stability, and function from two commonly consumed food products: cow’s milk and chicken eggs. This important work has been the first of its kind to demonstrate the bioavailability …

Diversity Of Yeast And Mold Species From A Variety Of Cheese Types, Nabaraj Banjara, Mallory J. Suhr, Heather E. Hallen-Adams

Department of Food Science and Technology: Faculty Publications

To generate a comprehensive profile of viable fungi (yeasts and molds) on cheese as it is purchased by consumers, 44 types of cheese were obtained from a local grocery store from 1 to 4 times each (depending on availability) and sampled. Pure cultures were obtained and identified by DNA sequence of the ITS region, as well as growth characteristics and colony morphology. The yeast Debaryomyces hansenii was the most abundant fungus, present in 79 % of all cheeses and 63 % of all samples. Penicillium roqueforti was the most common mold, isolated from a variety of cheeses in addition to …

Concomitant Uptake Of Antimicrobials And Salmonella In Soil And Into Lettuce Following Wastewater Irrigation, J. Brett Sallach, Yuping Zhang, Laurie Hodges, Daniel D. Snow, Xu Li, Shannon L. Bartelt-Hunt

Department of Civil and Environmental Engineering: Faculty Publications

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and …

Sourdough Lactic Acid Bacteria As Antifungal And Mycotoxin-Controlling Agents, Yousef I. Hassan, Ting Zhou, Lloyd B. Bullerman

Department of Food Science and Technology: Faculty Publications

Sourdough starter cultures are rich sources of endogenous lactic acid bacteria. The extended shelf lives of sourdough breads are attributed to a large array of organic acids and low-molecular-weight metabolites produced during the fermentation process. Different species belonging to the lactic acid bacteria group of microorganisms, mainly Lactobacillus and Leuconostoc, are increasingly gaining the attention as possible means for inhibiting mold growth in animal feed and human food chains. In addition, certain lactic acid bacteria strains isolated from sourdough starters were also shown to reduce mycotoxins concentrations in contaminated products either by binding or degradation. This short review will …

Characterization Of The Ecological Role Of Genes Mediating Acid Resistance In Lactobacillus Reuteri During Colonization Of The Gastrointestinal Tract, Janina A. Krumbeck, Nathan L Marsteller, Steven Frese, Daniel A. Peterson, Amanda Ramer-Tait, Robert W. Hutkins, Jens Walter

Department of Food Science and Technology: Faculty Publications

Rodent-derived strains of Lactobacillus reuteri densely colonize the forestomach of mice and possess several genes whose predicted functions constitute adaptations towards an acidic environment. The objective of this study was to systematically determine which genes of L. reuteri 100-23 contribute to tolerance towards host gastric acid secretion. Genes predicted to be involved in acid resistance were inactivated, and their contribution to survival under acidic conditions was confirmed in model gastric juice. Fitness of five mutants that showed impaired in vitro acid resistance were then compared through competition experiments in ex-germ-free mice that were either treated with omeprazole, a proton-pump inhibitor …

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 …

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%) …