College of Agriculture & Natural Resources

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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Subject: search.filters.subject.Probiotic

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Now showing 1 - 3 of 3
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    Synbiotic-like effect of linoleic acid overproducing Lactobacillus casei with berry phenolic extracts against pathogenesis of enterohemorrhagic Escherichia coli
    (Springer Nature, 2019-07-27) Tabashsum, Zajeba; Peng, Mengfei; Bernhardt, Cassendra; Patel, Puja; Carrion, Michael; Biswas, Debabrata
    Majority of enteric infections are foodborne and antimicrobials including antibiotics have been used for their control and treatment. However, probiotics or prebiotics or their combination offer a potential alternative intervention strategy for improving the host health and preventing foodborne pathogen colonization/infections in reservoir. Further, bioengineered probiotics expressing bioactive products to achieve specific function is highly desirable. Recently, we over-expressed mcra (myosin cross-reactive antigen) gene in Lactobacillus casei (Lc) and developed a bioengineered probiotics Lc + CLA which produce higher amounts of metabolites including conjugated linoleic acid (CLA). Furthermore, we also reported that prebiotic like components such as berry pomace (byproduct) phenolic extracts (BPEs) can enhance the growth of probiotics and improved the beneficial effects of probiotics. In this study, we evaluated the antimicrobial effect of modified Lc + CLA in combination of BPEs on growth, survival and pathogenesis of enterohemorrhagic Escherichia coli (EHEC).
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    BIOACTIVE LACTOBACILLUS CASEI IN REDUCING GROWTH AND COLONIZATION OF CAMPYLOBACTER JEJUNI
    (2018) Tabashsum, Zajeba; Biswas, Debabrata; Animal Sciences; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Campylobacter jejuni (CJ) is one of the pre-dominant causative agents of acute gastroenteritis in the US and occurs commonly through handling/consumption of contaminated poultry products. Probiotics with enhanced bioactive metabolites such as conjugated linoleic acids (CLAs) play crucial role in improving host health and act as antimicrobials. Further, prebiotic like components such as bioactive phenolics from berry pomace extract (BPE) can stimulate growth of beneficial microbes including Lactobacillus casei (LC) and inhibit bacterial pathogens in vitro. In this study, we aimed to assess efficiency of CLA overproducing LC (LC+mcra) alone or in presence of BPE against CJ. LC+mcra alone or LC+mcra with BPE reduced CJ growth, adhesion and invasion efficiency to cultured cells and also altered physicochemical properties, gene expressions related to virulence. These findings suggest, BPE and LC+mcra in combination may able to prevent CJ colonization in poultry and reduce cross-contamination, hence control foodborne infections with CJ in human.
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    Optimization of xanthan chitosan polyelectrolytic hydrogels for microencapsulation of probiotic bacteria
    (2011) Soma, Pavan Kumar; Lo, Martin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The effectiveness of microencapsulation system for targeted delivery of probiotics depends on its ability to protect cells from harsh gastrointestinal conditions of stomach followed by effectively releasing the cells in intestinal conditions. Oppositely charged xanthan and chitosan form stable polyelectrolytic hydrogels capable of encapsulating enzymes and cells. The present study aims at developing an effective microencapsulation system for probiotics by screening and optimizing the factors critical to xanthan-chitosan hydrogel (XCH) capsule formation. The changes in the core pH of the hydrogel capsule in response to simulated gastric juice (SGJ) were characterized. Increase in xanthan concentration and chitosan molecular weight improved the barrier properties, however, increasing complexation time beyond 40 min had the opposite effect. Increase in molecular weight of chitosan resulted in improved viability of probiotic bacteria, Lactobacillus acidophilus, after SGJ treatment, which could be attributed to the differences in hydrogel membrane thickness at the surface of capsule, as evidenced by scanning electron micrographs (SEM). Introducing XCH capsules made with high molecular weight (HMW) chitosan into xanthan solution resulted in the formation of xanthan-chitosan-xanthan hydrogel (XCXH) capsules. Unlike HMW and medium molecular weight (MMW) chitosan, low molecular weight (LMW) chitosan did not form the outer layer beyond XCH, suggesting the significance of chitosan molecular weight in the formation of XCXH. The increased hydrogel thickness of XCXH capsules formed with HMW chitosan compared to XCH capsules rendered better retention of cells in SGJ treatment for a longer period of time, further suggesting the importance of membrane thickness on the hydrogel stability and its barrier properties. Furthermore, complete release of cells from XCXH in simulated intestinal fluid (SIF) was extended by approximately an hour compared to XCH capsules. Smaller, nozzle-sprayed XCXH capsules using HMW chitosan protected probiotic bacteria in SGJ albeit one-log reduction in its protective efficacy compared to syringe extruded capsules. When incorporated into stirred yogurt, XCXH microcapsules improved the viability of L. acidophilus by ~1 log CFU/ml between 15 and 30 days of storage. The stability of bacteria against bile salts was significantly improved, enabling the delivery of prescribed number of cells to attain the claimed health benefits.