Theses and Dissertations from UMD

Permanent URI for this communityhttp://hdl.handle.net/1903/2

New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM

More information is available at Theses and Dissertations at University of Maryland Libraries.

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2018 - 20202

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Subject: search.filters.subject.Gut microbiota

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    CHEMICAL COMPOSITIONS OF SELECTED SEED FLOUR EXTRACTS AND THEIR POTENTIAL HEALTH BENEFICIAL PROPERTIES
    (2020) Choe, Uyory; Yu, Liangli Lucy; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The rationale of the current dissertation research is to investigate health beneficial components and properties of blackberry, broccoli, carrot, cucumber, and milk thistle seed flours. This can lead to potential utilization of these seed flours in nutraceuticals and functional foods. Also, this can add value to oil manufacturers and the seed producers while reducing environmental contaminations. Blackberry, broccoli, carrot, cucumber, and milk thistle seed flours were extracted with 50% acetone and evaluated for their phytochemical compositions along with their potential gut microbiota modulating, free radical scavenging, and anti-inflammatory and anti-proliferative capacities. Thirteen, nine, ten, and fifteen compounds were detected in the blackberry, broccoli, carrot, and milk thistle seed flour extracts, with sanguiin H6, glucoraphanin, kaempferol-3-O-rutinoside, and silychristin as the primary component of each, respectively. All five seed flour extracts enhanced total number of gut bacteria and altered the abundance of specific bacterial phylum or genus in vitro. The blackberry seed flour extract had the greatest relative DPPH radical scavenging capacity and ABTS•+ scavenging capacity values of 362 and 267 μmol trolox equivalent (TE)/g, respectively. Milk thistle seed flour had the greatest oxygen radical absorbing capacity and hydroxyl radical (HO•) scavenging capacity values of 634 and 10420 μmol trolox equivalent (TE)/g, respectively. Also, all five seed flour extracts suppressed LPS induced IL-1β mRNA expressions in J774A.1 cells and the proliferation of LNCaP prostate cancer cell line. The results might be used to promote the value-added food utilization of these seed flours in improving human health.
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    STIMULATION OF GROWTH AND METABOLITES PRODUCTION OF LACTOBACILLUS IN CONTROL OF ENTERIC BACTERIAL PATHOGEN INFECTION AND IMPROVING GUT HEALTH
    (2018) Peng, Mengfei; Biswas, Debabrata; Molecular and Cell Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Foodborne enteric diseases cause millions of illness and thousands of deaths annually in the United States. Major enteric bacterial pathogens include Salmonella, enterohemorrhagic Escherichia coli O157:H7 (EHEC), Campylobacter, Listeria, Shigella, Vibrio, and Yersinia which account for more than 90% cases of culture-confirmed infections. Among these causative agents, Salmonella enterica is responsible for the highest rate of hospitalization and EHEC has the lowest infectious dose. Their pathogenesis involves numerous virulent factors whereas their colonization and invasion on host gut intestine mainly depend on the type III secretion system. The prevention of foodborne enteric diseases is of great concern to public health professionals, farmers, and food producers. Due to the increased public health concern about antibiotic-resistance dissemination, alternative strategies such as pro-commensal approach by applying probiotics, prebiotics, and combination of both (synbiotics) are of interests for prevention and therapy of foodborne enteric diseases. In this study, we both in vitro and in vivo evaluated the preventive capabilities of Lactobacillus against enteric pathogenic bacterial colonization and infection. Functional food cocoa and peanut containing prebiotic-like ingredients selectively promoted the growth of beneficial bacteria and stimulated the production of bio-active metabolites especially conjugated linoleic acids in Lactobacillus. We also detected the synergistic effects of Lactobacillus and cocoa/peanut on competitive exclusion of S. Typhimurium and EHEC, alteration on physicochemical properties, disruption of host-pathogen interactions, and down-regulation on virulence gene expressions. Furthermore, with homologous recombination, we overexpressed myosin cross-reactive antigen gene encoding linoleate isomerase in L. casei and improved the efficiency in their linoleic acids production as well as the gut intestinal adherence and colonization. By applying genetically engineered LC-CLA, S. Typhimurium and EHEC were much effectively controlled and restricted from all aspects in vitro mentioned before. Additionally, the in vivo pre-administration of LC-CLA reduced S. Typhimurium gut intestinal colonization/infection in a significant level and induced anti-inflammatory effects, which benefitted the overall mice gut health. Our findings established a baseline upon which self-promoting probiotic independent from prebiotic in prevention or treatment against enteric diseases can be explored.