Food Microbiology Commons^™

Enhancing Lovastatin Biosynthesis In Oyster Mushrooms (Pleurotus Ostreatus) Using Phytohormones, Fransisca Astrid Mustafa, Mamat Kandar, I Nyoman Pugeg Aryantha

Makara Journal of Science

The biosynthesis of lovastatin, the anti-cholesterol compound, in oyster mushrooms (Pleurotus ostreatus), has the potential to be enhanced by utilizing phytohormones, which activate the expression of certain genes. This research aimed to determine the best type and concentration of phytohormone among auxin, gibberellin, and cytokinin, as well as the best mycelial colonization percentage in F2 medium to realize the greatest increase in lovastatin biosynthesis in oyster mushrooms. Lovastatin was extracted from the fruiting bodies and mycelia and analyzed by spectrophotometry. The analysis of CYP450 linked to lovastatin biosynthesis was conducted by quantitative polymerase chain reaction (qPCR) using samples containing …

Filth Flies As A Vector For Some Pathogenic Bacteria Transfer, Ahmet Buyukyavuz

All Dissertations

Two separate sets of experiments were conducted to determine the transfer of bacteria by flies. An Escherichia coli ampicillin-resistant strain with a fluorescent gene was used during the experiments. The first set of experiments were divided into two trials to measure the transfer of E. coli by fruit flies to apple slices and bologna during short term exposure. Short time exposure (1, 5 and 15 min) of flies to inoculated apple slices were tested in the first trial to determine the transfer of E. coli to flies. No difference (P>0.05) in the number of bacteria transferred to flies were …

Optimizing Soil Nutrient Management To Improve Dry Edible Bean Yield And Protein Quality, Emily Jundt

Dissertations, Theses, & Student Research in Food Science and Technology

Soil nutrient management is of the utmost importance to ensure crop yields are maximized to feed the world’s growing population. Micro and macronutrient deficiencies can be detrimental to plant growth and cause a drastic reduction in yield. Optimization of nutrient management needs extensive research. Nutrients such as nitrogen increase crop yield, even in legumes capable of using a large amount of nitrogen (N) via biological N fixation. Iron (Fe) fertilizers are also crucial for legumes as they are susceptible to Fe deficiency induced chlorosis.

Dry edible beans (Phaseolus vulgaris) are leguminous plants and excellent dietary protein sources. Great …

Determining The Effects Of Maternal Adiposity On Preterm Neonatal Microbiome And Short Chain Fatty Acid Profiles, Dalton James, William A. Clark Phd, Kristy L. Thomas

Undergraduate Honors Theses

The gut microbiota and its metabolites have vast impacts on the human digestive system, immune system, and health outcomes. Short chain volatile fatty acids (SCVFAs) present in feces can be representative of the interactions of the microbiota present in the gut. Low microbiota diversity in the human gut is highly associated with obesity and adverse health outcomes. Furthermore, the maternal microbiome has a direct impact on neonatal microbiota through various pathways such as environment, skin flora, breast milk composition, and vaginal secretions. This study is aimed to further understand the associations between various factors (maternal adiposity, gestational time, length of …

Fusarium Species Structure In Nebraska Corn, Yuchu Ma

Dissertations, Theses, & Student Research in Food Science and Technology

Fusarium species are known to infect corn and cause significant yield losses and mycotoxin contamination worldwide. In this study, we investigated the diversity of Fusarium species infecting corn in Nebraska and their potential to produce fumonisins and trichothecenes. A total of 259 Fusarium isolates were collected from different corn tissues (ear, stalk, and root), revealing a significant association between the various Fusarium species complexes and different plant parts (p < 0.05). Fusarium incarnatum-equiseti species complex (FIESC) was the most widespread and abundant, followed by the Fusarium sambucinum (FSAMSC) and Fusarium fujikuroi species complexes (FFSC). In the subsequent analysis, we investigated the mycotoxin …

Bifidobacterial Metabolism Of Fucosylated Human Milk Oligosaccharides Influences Structure And Function Of The Infant Gut Microbiome

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. …

Impacts Of Temperature And Salt Concentrations For Thermal Inactivation Of Salmonella In Moisture Enhanced Reconstructed Chicken Patties, Alik D. Browning

Graduate Theses, Dissertations, and Problem Reports

The purpose of this experiment is to determine the thermal kinetic parameters of Salmonella in moisture-enhanced, reconstructed ground chicken patties as affected by temperatures and salt concentrations. Salmonella is responsible for 35% of the foodborne illnesses associated with poultry products (Batz et al., 2011). Nonintact reconstructed chicken meat is mixed with brine solutions containing various salt and polyphosphate concentrations to increase water-holding capacity, decrease cooking losses, improve sensory tasting scores, and maintain the good quality of completed chicken products (Gill et al., 2004). Increasing salt concentrations within meats can increase the thermal inactivation of pathogens. In this study, Salmonella Typhimurium …

Microstructure And Sensory Attributes Of Rabbiteye Blueberries Subject To Osmotic Dehydration And Two Freezing Methods, Antonio Carlos Garcia

Theses and Dissertations

Frozen, thawed and osmotically-dehydrated highbush (HB) (Vaccinium corymbosum) and rabbiteye (RB) (V. virgatum) blueberries were analyzed under a scanning electron microscope (SEM) to observe microstructural differences in their skin. Rabbiteye blueberries of both frozen, thawed and osmotically-dehydrated treatments, had thicker skins than highbush blueberries. Rabbiteye blueberries, collected from local farms, packed and blast frozen (PBF), had thinner skins than individually quick-frozen (IQF) blueberries. Washing berries prior to freezing had no effect on skin thickness. Sensory analysis of samples determined there were no differences (p > 0.05) between PBF and IQF methods and species with respect to skin intactness, grittiness, sweetness, and …

Seasonal Trends And Sampling Time Of Day On Overall Microbial Population And Indicator Organisms In Catfish Parts And Catfish Processing Environment, Maria Gabriela Hidalgo-Sindoni

Theses and Dissertations

Commercial production of catfish is the leading aquaculture industry in the United States. Production in Mississippi, Louisiana, Alabama, and Arkansas representing 96% of the total catfish sales in the USA. In 2017, the USDA-FSIS added testing of generic Escherichia coli and Enterococcus to the sampling of Siluriformes. The incidence of Escherichia coli in fish and seafood has been associated with possible fecal matter contamination. However, this indicator bacteria could also be a part of the natural microflora of catfish ponds where processing plants collect hybrid catfish. Aerobes, Psychrotrophs, Coliforms, Escherichia coli, and Enterobacteriaceae counts among environmental, liquid and fish …

Antimicrobial Efficacy Of A Citric Acid/Hydrochloric Acid Blend, Peroxyacetic Acid, And Sulfuric Acid Against Salmonella On Inoculated Non-Conventional Raw Chicken Products, Emma Nakimera

Dissertations, Theses, & Student Research in Food Science and Technology

The utilization of non-conventional chicken parts as human food varies widely across countries. The high prevalence of Salmonella, especially in the giblets, poses a high risk to public health. Poultry processors have implemented multiple hurdle technology to reduce this gram-negative pathogen in chicken parts. This study was conducted to evaluate the antimicrobial efficacy of a commercial blend of citric acid/ hydrochloric acid (CP), peroxyacetic acid (PAA), and sulfuric acid (SA) in reducing Salmonella inoculated on two chicken giblets: livers and hearts. Chicken hearts and livers were inoculated (6 log CFU/ml of rinsate) by individually immersing them in a cocktail …

Evaluating The Efficacy Of Germination And Fermentation In Producing Biologically Active Peptides From Pulses, Ashley Newton

Dissertations, Theses, & Student Research in Food Science and Technology

Recently, there has been a profound increase in demand of plant-based proteins, especially pulse proteins. However, pulses contain high concentrations of antinutritional factors that hinder the digestibility of proteins. Processing techniques such as enzymatic hydrolysis, microbial fermentation, and physical processing modulate nutritional quality and functionality of pulses. Processing also releases peptides from parent proteins that exhibit health-beneficial bioactivity against various disease risk factors. In this study, germination, gastrointestinal digestion, and microbial fermentation were evaluated to determine the nutritional quality and release of bioactive peptides during and after processing.

Germination of chickpeas (Cicer arietinum L.) modulated the protein profile, and …

The Invisible Meat Microcosmos - Investigations Of Processed Meats' Specific Spoilage Organisms, Rebecca Furbeck

Theses and Dissertations in Animal Science

As humankind grows in population, so will our need to compete against bacterial populations which spoil foodstuffs before we are able to consume them. This dissertation aims to identify the bacterial communities responsible for meat spoilage, and the mechanisms that govern the behaviors of these organisms. The literature review summarizes the state of knowledge regarding factors that influence meat microbiome composition, and how analytical methods can influence research outcomes. Study 1 aimed to identify the impact of additional ingredients and processing steps on the microbial ecology of processed turkey products. The main specific spoilage organisms (SSOs) belonged to the orders …

Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas

Graduate Theses and Dissertations

Historically, low-water activity (aw) foods (aw <0.65) were considered to be microbiologically safe for consumption. However, these foods have been implicated in outbreaks of pathogens such as Salmonella enterica, at a frequency that surely challenges this assumption of safety. Although usually implicated in outbreaks involving poultry and egg products, Salmonella spp. have frequently been the culprit in several outbreaks and recalls associated with low-water activity foods (LWAF) due to contamination resulting from the environment, animals, or even the employees during pre-or post-processing. One such LWAF that has been associated with Salmonella spp. outbreaks is milk powder. Milk powders are used in a variety of products ranging from infant formula to confectionary goods. With their widespread use, improving their safety is imperative. A key step in improving their safety is to thoroughly investigate preventive controls related to milk powder processing. The Food Safety Modernization Act (FSMA) established the Preventive Controls for Human Foods Rule, which mandates that processors design and establish a food safety plan outlining any potential hazards and the steps they will take to ensure those hazards do not compromise the safety of the product. Presently, the dairy industry does not have an established kill-step for milk powders post-spray drying. Spray drying may reduce some microbial populations, however, desiccation(e.g., spray drying) is not considered a kill-step. The work outlined in this thesis aims to assist our dairy industry partners in establishing their own thermal process for milk powders post-spray drying. Moisture sorption isotherms of two milk powders (nonfat dry milk: NFDM and a milk protein concentrate with 85% protein content: MPC-85) were determined and showcased that the temperatures at which the isotherms were determined (23, 40, or 60°C) significantly affected both the adsorption and desorption isotherms (p<0.0001) for each powder. Secondly, the thermal inactivation kinetics of Salmonella spp. in both powders were evaluated at two different water activities (0.20 and 0.30) and three temperatures (75, 80, and 85°C) to determine the effect of water activity on the thermal resistance of a cocktail of Salmonella spp. The D-values of Salmonella were heavily influenced by the thermal treatment temperature (p< 0.0001), but not the water activity (p >0.05). The overall findings contained within this thesis provide valuable information about the thermal inactivation kinetics of Salmonella spp. to our partners in the dairy industry so that they may implement an appropriate thermal process for their milk powders.

Identification Of Gut Microbiome Composition Responsible For Gas Production, Erasme Mutuyemungu

Dissertations, Theses, & Student Research in Food Science and Technology

Gas production remains a significant barrier to increasing intake of dietary fiber-containing foods for many consumers. Therefore, this thesis is comprised of two studies focusing on the role of the gut microbiome in contributing to gas production during fermentation of dietary components. Previous studies have reported significant correlations between Megasphaera elsdenii and gas production during fermentation of pulses. Therefore, the objective of the first study was to determine the role of M. elsdenii in gas production by the microbiome during fermentation of foods commonly associated with gas production. Human fecal microbiomes were separated based on the presence (Me+) or absence …

Safety Assessment Of Novel Foods And Food Proteins, Niloofar Moghadam Maragheh

Dissertations, Theses, & Student Research in Food Science and Technology

The global food market needs to grow and supply food demand to feed the growing world population. Alternative food proteins, including novel sources of safe foods and ingredients, are the candidates that could provide more environmentally sustainable choices, animal welfare, and consumers health. Novel foods and food proteins must undergo premarket safety evaluations including allergenicity assessment to reduce the risk of cross-reactivity with known allergens and uncharacterized risk to food allergic individuals. This research addressed the safety assessment of some novel foods and food ingredients using the study of stability of proteins in pepsin and sequence identity analysis in the …

Occurrence Of Hydroxyproline In Proteomes Of Higher Plants, Olivia Huffman

Dissertations, Theses, & Student Research in Food Science and Technology

Food allergies affect millions of individuals across the United States and worldwide. Peanut allergies are among the most severe food allergies because of their potentially life-threatening symptoms and lifelong persistence. Potent peanut allergen, Ara h 2, is known to contain an amino acid motif containing the posttranslational modification, hydroxyproline (HyP). HyP is associated with immunogenic response when present both in Ara h 2 and in timothy grass pollen allergen, Phl p 1. To further explore the presence of HyP in higher plants and specifically to investigate its potential presence in commonly allergenic plants, a study of 26 plant seeds was …

Lactic Acid Bacteria Isolated From Fresh Vegetable Products: Potential Probiotic And Postbiotic Characteristics Including Immunomodulatory Effects, Fatima Khaled Alameri

Theses

The ability to perform effectively in the gastrointestinal system (GIT) is one of the most significant criteria for selecting the best probiotic bacteria. Thus, the present study aimed to investigate the potential probiotic characteristics of some selected lactic acid bacteria (LAB) isolated from vegetable products. Probiotic characteristics included tolerance to acid and bile, cholesterol removing ability, bile salt hydrolysis, resistance against lysozyme and antibiotics, production of exopolysaccharides (EPS), antimicrobial and hemolytic activities, and cell surface characteristics (auto-aggregation, co-aggregation, and hydrophobicity). Out of 46 isolates, 17 isolates that exhibited remarkable survivability under gastrointestinal conditions were selected for further analysis. Almost all …

The Rapid Enumeration Of A Mixed Culture Of S. Cerevisiae & L. Plantarum In Beer Using Image-Based Cytometry, Kevin M. Kennedy

Electronic Theses and Dissertations

Mixed cultures are prevalent in the food industry. From sour beer to sourdough bread, mix culture popularity is growing. A number of microbiological mixtures are used in these unique fermenting processes to create distinctive flavor profiles of consumers’ favorite foods. Although mixed cultures seem ubiquitous, they are often not well enumerated. The aim of this thesis was to create a novel rapid image-based cytometry method to enumerate mixed cultures in beer. Imaged-based cytometry can be used to rapidly enumerate mixed microbial cultures, as opposed to traditional plate counting methods that can take days to grow and count. A novel method …

Prevention Of Inflammatory Bowel Disease By Broccoli-Sourced And Microbially-Produced Bioactives, Johanna M. Holman

Electronic Theses and Dissertations

Inflammatory Bowel Diseases (IBD) are chronic, reoccurring, and debilitating conditions characterized by inflammation in the gastrointestinal tract, some of which can lead to more systemic complications and can include autoimmune dysfunction, a change in the taxonomic and functional structure of microbial communities in the gut, and complicated burdens in a person’s daily life. Like many diseases based in chronic inflammation, research on IBD has pointed towards a multifactorial origin involving factors of the host’s lifestyle, immune system, associated microbial communities, and environmental conditions. Too often, research focuses on just one aspect of IBD or uses one model with a narrow …

Comparative Assessment Of Human Exposure To Antibiotic-Resistant Salmonella Due To The Consumption Of Various Food Products In The United States, Yifan Wu

Dissertations, Theses, & Student Research in Food Science and Technology

Antibiotic resistance (AR) was increasingly recognized as a global and national problem. Prevention efforts are hampered by a lack of complete understanding of how transmission pathways contribute to human AR exposure. Many reports have indicated the presence of antibiotic-resistant bacteria in foods at retail, suggesting that food consumption, animal-derived foods in particular, can represent a significant source of AR exposure among consumers. The presence of Salmonella, including antibiotic-resistant Salmonella, has been frequently reported in terrestrial animal-derived foods such as meat, poultry, and dairy products, as well as in aquaculture products. Identification of the significant food sources that harbor …