Food Microbiology Commons^™

Screening Of Biocontrol Organisms For The Management Of Phytopathogenic Fungi And Foodborne Pathogens On Produce, Antoinette Boyee De Senna

Master's Theses

The multibillion dollar agricultural industry is an important part of the United States economy, and the management of factors that affect crop and human health is imperative to maintaining this economic sector. The fungi Botrytis cinerea, Fusarium pallidoroseum, and Fusarium moniliforme are the causative agents of several plant diseases and can cause significant crop loss both before and after harvest in commodities such as strawberries, lettuce, citrus, and grains. Fungicides are employed to control these phytopathogens, but the use of these chemicals has led to an increase in fungicide resistance and may negatively affect the environment and human …

The Effects Of Phytochemical Tannin-Containing Diets On Animal Performance And Internal Parasite Control In Meat Goats, Chassity Wright

College of Agriculture, Environment and Nutrition Sciences Graduate Theses and Dissertations

ABSTRACT

The Effects of Phytochemical Tannin-Containing Diets on Animal Performance and Internal Parasite Control in Meat Goats

By

Chassity Wright

Haemonchus contortus (H. contortus) resistance has been reported against almost all chemical anthelmintics available for its control. H. contortus has a remarkable ability to develop resistance and threatens the viability of the goat industry in many regions of the world. Consequently, there is an urgent need to understand the genetic mechanisms underlying anthelmintic resistance and to discover new alternative methods of chemical and non-chemical control. With chemical anthemintics failing, this has led to the evaluation of plants as a natural …

Antimicrobial Susceptibility Of Listeria Monocytogenes To Bacteriophage Listex™ P100 In Alfalfa Sprouts (Medicago Sativa), Tushar Sawant

Food Science (MS) Theses

The seed germination process during sprout production provides suitable environmental conditions for the growth of pathogenic bacteria, such as Listeria monocytogenes. A potential way to control this bacterial growth is through the use of bacteriophages, which are naturally occurring viruses that specifically attack bacterial targets and have been shown to be effective antimicrobials in some foods. Therefore, the objective of this study was to evaluate the antimicrobial susceptibility of L. monocytogenes to bacteriophage on alfalfa sprouts during seed germination and subsequent refrigerated storage at 4 °C. Alfalfa sprout seeds were dip-inoculated with 5.5 x 105 CFU/ml L. monocytogenes serogroups 1 …

The Effects Of Electrostatic Spraying With Organic Acids In The Disintegration Of Biofilms Formed By E.Coli O157:H7 And Salmonella Typhimurium On Spinach And Cantaloupe, Ahmad Almasoud

Graduate Theses and Dissertations

Outbreaks from the consumption of fresh produce are a concern in the United States. The consumptions of fresh produce have increased recently which expose a large segment of society to such outbreaks. Spinach and cantaloupe are minimally heated or processed before consumption which makes them a possible source of foodborne illness. The objective of this research was to investigate the effect of organic acids alone and in combination to reduce attached Salmonella Typhimurium (S.T) and Escherichia coli O157:H7 (E.coli) on spinach and cantaloupe, and to disintegrate biofilm formed by these pathogens by electrostatically spraying with two organic acids. To quantify …

Direct Fermentation Of Sweet Potato Starch Into Lactic Acid By Lactobacillus Amylovorus: The Prospect Of An Adaptation Process, Winifred Akoetey

Graduate Theses and Dissertations

Several studies have verified that lactic acid bacteria are capable of directly producing lactic acid from starch. One of these bacteria, L. amylovorus, has been studied using corn, potato, and cassava starches. However, the use of sweet potato starch, a widely available starch, has not been considered. Furthermore, there exists the possibility that the efficiency of lactic acid production can benefit from the systematic exposure of bacteria to increasing concentrations of a particular starch. In this work, fermentation studies were conducted to understand the adaptation of L. amylovorus to rising concentrations of sweet potato starch. L. amylovorus was cultured in …

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 …

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 …

Application Of Essential Oil Compounds And Bacteriophage To Control Staphylococcus Aureus, Anisha Ghosh

Graduate Theses and Dissertations

Staphylococcus aureus is one of the most important pathogens, causing various diseases in humans and animals. In addition, S. aureus is a common foodborne pathogen. As methicillin- resistant S. aureus (MRSA) becomes increasingly prevalent, controlling this pathogen in animals and humans with standard antibiotic treatment has become challenging. Combinations of different antimicrobial agents represent one of the most promising approaches for combating multidrug - resistant bacteria both for treatment of clinical disease as well as in food. Two such antimicrobials with potential application in the food industry include essential oils (EO) and host-specific bacteriophage (phage). The objectives of this study …

Phenotypic And Functional Genomics Analyses Of Salmonella For Food Safety Applications, Turki Dawoud

Graduate Theses and Dissertations

Non-typhoidal Salmonella species have been major foodborne zoonotic pathogens causing serious problems in public health and food industry for several decades. Numerous Salmonella species have frequently been associated with different food commodities mainly poultry meat, eggs, and their products. This dissertation begins with a literature reviews discussing many aspects of Salmonella generally; and subsequently focused on two serotypes, Salmonella Enteritidis and S. Typhimurium as they are at the top of all other serovars responsible for most illness cases and outbreaks. In addition, some Salmonella strains have exhibited their ability to tolerate and survive many food processing treatments. We can divide …

Functional Screening Of The Cronobacter Sakazakii Baa-894 Genome Reveals A Role For Prop (Esa_02131) In Carnitine Uptake, Audrey Feeney, Roy D. Sleator

Department of Biological Sciences Publications

Cronobacter sakazakii is a neonatal pathogen responsible for up to 80% of fatalities in infected infants. Low birth weight infants and neonates infected with C. sakazakii suffer necrotizing enterocolitis, bacteraemia and meningitis. The mode of transmission most often associated with infection is powdered infant formula (PIF) which, with an aw of ∼0.2, is too low to allow most microorganisms to persist. Survival of C. sakazakii in environments subject to extreme hyperosmotic stress has previously been attributed to the uptake of compatible solutes including proline and betaine. Herein, we report the construction and screening of a C. sakazakii genome bank and …

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 …

Influence And Characterization Of Microbial Contaminants Associated With The Fda Bam Method Used To Detect Listeria Monocytogenes From Romaine Lettuce, Christopher E. Bach

Open Access Theses

Over the past few decades in the US, fresh produce commodities have become increasingly prevalent vehicles for the attribution of foodborne illness. Recent outbreaks of the bacterial foodborne pathogen Listeria monocytogenes linked to fresh produce highlight this immediate issue facing food safety. The most widely used method to screen L. monocytogenes from food matrices in the US is the Bacteriological Analytical Manual (BAM) developed by the Food and Drug Administration (FDA). Detection of this pathogen from all foods is primarily accomplished by using four FDA approved Listeria selective media: Oxford (OXA), modified Oxford (MOX), Lithium chloride-phenylethanol-moxalactam fortified with esculin and …

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 …

Microbial Safety And Quality Of Fresh Herbs From Los Angeles, Orange County, And Seattle Farmers’ Markets, Donna J. Levy, Nicola K. Beck, Alexandra L. Kossick, Taylor Patti, J. Scott Meschke, Melissa Calicchia, Rosalee S. Hellberg

Food Science Faculty Articles and Research

BACKGROUND: Farmers' markets have been growing in popularity in the United States, but the microbial quality and safety of the food sold at these markets is currently unknown. The purpose of this study was to assess the microbial safety and quality of fresh basil, parsley and cilantro sold at farmers' markets in the Los Angeles, Orange County and greater Seattle areas.

RESULTS: A total of 133 samples (52 basil, 41 cilantro and 40 parsley) were collected from 13 different farmers' markets and tested for Salmonella and generic Escherichia coli. One sample (parsley) was confirmed positive for Salmonella and 24.1% of …

Antimicrobial Efficacy Of Natural Bioactive Compounds And High Pressure Processing Against Potential Pathogens In Infant Foods, Hayriye Cetin-Karaca

Theses and Dissertations--Animal and Food Sciences

This study investigated the antimicrobial efficacy of bioactive plant compounds along with high pressure processing (HPP) against pathogens Bacillus cereus and Cronobacter sakazakii in infant formula and infant rice cereal. The influence of these applications on antimicrobial activity, shelf-life and sensory attributes of infant foods were examined.

Trans-cinnamaldehyde (TC), (-)-Epigallocatechin gallate (EGCG) and [10]-Gingerol (GI) were incorporated (0.05%) in infant rice cereal reconstituted with infant formula. The cereal was inoculated with either B. cereus (ATCC 14579) or B. cereus spores (10⁷-10⁸ log CFU g^-1). All the samples were stored at 7, 23 or 37°C for …

Increasing The Nutritional Value Of Canola Meal Via Fungal Bioprocessing, Jason R. Croat

Electronic Theses and Dissertations

The main limitation of meals from canola and other Brassica spp. is the presence of glucosinolates (GLS), which are anti-nutritional and can even be toxic at high ingestion levels. Furthermore, large amounts of GLS can reduce palatability for livestock and thus reduce intake and growth rates. For this reason canola was bred to contain lower levels of GLS (<30 >μmol/g) and erucic acid (< 2%). However, feed inclusion rates are still limited to ~30%, and this reduces the value of canola meal. The goal of this thesis was to optimize a pretreatment and fungal conversion process to enhance the nutritional value of canola meal. Various combinations of physical/chemical pretreatments, fungal cultures, and incubation methods were investigated to metabolize GLS into cell mass, CO2, or other non-toxic components. These treatments also served to hydrolyze canola meal fiber into carbohydrates which were then metabolized by the fungi into single cell protein. Solid-state incubation conditions were initially tested, since filamentous fungi are well adapted to grow at lower moisture levels, and this would potentially reduce contamination issues with bacteria. Flask trials were performed using 50% moisture, hexane extracted (HE) or cold pressed (CP) canola meal, with incubation for 168 h at 30ºC. On HE canola meal Trichoderma reesei (NRRL-3653) achieved the greatest increase in protein content (23%), while having the lowest residual levels of sugar (8% w/w) and GLS (0.4 μM/g). On CP canola meal T. reesei (NRRL-3653), Aureobasidium pullulans (NRRL-58522), and …

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 …