Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Publisher: search.filters.publisher.Izmir Institute of TechnologySubject: search.filters.subject.Probiotics

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Now showing 1 - 4 of 4
  • Master Thesis
    Modulating Akkermansia Muciniphila by Probiotics for Obesity Management
    (Izmir Institute of Technology, 2021) Kamber, Aslıhan; Harsa, Hayriye Şebnem; Bulut Albayrak, Çisem
    The aim of this thesis is to investigate the potential of lactic acid bacteria (LAB) having probiotic properties to trigger Akkermansia muciniphila as anti-obesity candidate. Artisanal strains of LAB were evaluated in terms of stability in gastrointestinal conditions, mucin/mucus non-utilization properties, growth in the presence of mucin, adhesion to the mucin/mucus layer, biofilm formation, lactate production abilities, antimicrobial properties, HT-29 cell binding and mucin/mucus thickness increment abilities. Among 40 strains, 17 of LAB including 6 olive isolates were selected for their tolerance to gastrointestinal conditions and analyzed for further abilities e.g., mucin promotion potential. Most of them (13 of the 17 bacteria) remained viable in the range of 106-108CFU/mL in the simulated gastric juice, and these bacteria continued their viability in the range of 105-107 CFU/mL in the simulated intestinal fluid. Besides, 6 reference and 7 L. bulgaricus isolates did not utilize the mucin and showed no or negligible growth in the presence of mucin. Additionally, 13 of the 17 bacteria adhered to mucin layer with variable degree of binding between 41.03-65.37%. Furthermore, variable degree biofilm formation efficiencies can also support their existence and adhesion to intestinal cells. Varying amounts of lactate by 7 LAB were produced (6.51-18.17 g/L) and this ability is another important criteria for supporting mucus pathway. All those strains adhered to HT-29 cell line and they showed significant increase in mucin thickness by comparing the control. L. plantarum C47 and Lactobacillus AK50 isolates were selected as the antiobesity prototype candidates for their desirable attributes.
  • Master Thesis
    Development of Functional Chocolate Using Gamma-Amino Butyric Acid Producer Probiotic: Prominent To Alleviate Anxiety Disorder
    (Izmir Institute of Technology, 2019) Özer, Merve; Harsa, Hayriye Şebnem; Sezgin, Efe
    The purpose of this study was screening of four probiotics to investigate for their gamma-aminobutyric acid producing capabilities. Lactobacillus rhamnosus NRRL B- 442 strain has been selected for its maximum gamma-aminobutyric acid concentration. In this study, a new chocolate product has been developed by incorporation of probiotic cells; stability of the probiotics was improved by microencapsulation by water-in-oil emulsion technique using whey-pullulan complex. Survival rates of microencapsulated and free-cells of probiotic bacteria in chocolate have been compared. Probiotic counts were found as 6.75 log CFU/g and 7.20 log CFU/g in chocolate, for encapsulated and free-cells, respectively, at the end of 60 days. High cell counts and increased cell resistances were remained at 4oC when compared at 25oC, in chocolate samples. Furthermore, probiotics did not affect the physical, chemical and sensory properties of chocolate, whereas the texture analysis showed an increase in the hardness of free-cell in chocolate bacteria on the 0th and 60th day. Survival rate of microencapsulated bacteria in chocolate samples was observed at higher percentage 87% than free-cell bacteria e.g. 75% during simulated in-vitro analysis. Consequently, Lb. rhamnosus with the highest GABA producing capability may provide insight for patients having an anxiety disorder, since this strain has been thought as having a therapeutic effect. A new functional food model was developed for “Gut- Brain Axis” phenomena since the chocolate could be accepted as a good carrier for probiotics.
  • Master Thesis
    Developing Probiotic Lozenges To Improve Oral Health
    (Izmir Institute of Technology, 2019) Elvan, Menşure; Harsa, Hayriye Şebnem; Baysal, Ayşe Handan
    Recently, there is a great need to overcome complaints about oral health from children, mental and physically handicapped people who are inadequate in oral hygiene and after chemotherapy of cancer patients. With reduced body resistance, opportunistic Streptococcus mutans and Candida albicans in the mouth become dominant, causing disruption of oral health. Therefore, the effect of lactic acid bacteria on pathogens was investigated in order to protect oral health with the thesis study. Lactobacillus pentosus NRRL-B 227 was determined among the probiotic bacteria tested for this purpose and its activity on the pathogen Streptoccocus mutans ATCC 25175 and Candida albicans DSMZ 5817 was found in broth microdilution, agar overlay and planktonic culture assays except disc diffusion test. To reduce the number of pathogens in oral microflora, lozenges containing L. pentosus were developed. Three different lozenges with encapsulated and free bacteria and control lozenge were produced, kept at different temperatures; 4⁰C and 25⁰C. No significant decrease in viability of the encapsulated probiotic strain after lozenge production and storage at 4°C was observed, the probiotic amount in the lozenge initially counted as 7.84 log CFU/g, while 7.73 log CFU/g at the end of 3 months shelf life. However, lozenges stored at 25⁰C probiotics lost their vitality after one month. Additionally, lozenges containing free bacteria have lost viability rapidly. Color and water activity were observed differently in the formulations (p <0.05). The formulations maintained their microbiological safety during storage. Lozenge with L. pentosus NRRL-B 227 has a significant potential for improving oral health and provides an alternative to the diversification of products containing probiotics.
  • Master Thesis
    Isolation, Characterization, Determination of Probiotic Properties of Lactic Acid Bacteria From Human Milk
    (Izmir Institute of Technology, 2007) Yavuzdurmaz, Hatice; Harsa, Şebnem
    Probiotics mean live microorganisms that have beneficial effects on their host.s health. Although probiotic strains can be isolated from many sources; for human applications the main criteria is being human origin.Breast milk is an important nutrient source for neonates. Lots of studies showed that this fluid has beneficial effects on the health of neonates. One reason of being beneficial is explaining by the microflora of human breast milk including beneficial lactic acid bacteria.In this study, isolates were identified by biochemical and molecular characterization and also probiotic properties of lactic acid bacteria, isolated from human milk were investigated.Three of the isolates were observed as potential probiotic. Two of them are bacilli and the other is cocci. These isolates showed resistance to stomach pH (pH 3,0), tolerance against 0,3% bile concentration and antimicrobial activity against Salmonella thyphimurium CCM 5445, Escherichia coli O157:H7 NCTC 129000 and Escherichia coli NRRL B-3008. After investigation the probiotic properties of these isolates, they were identified by biochemical characterization techniques and molecular identification by using amplification and restriction fragment length polymorphism (RFLP) of 16S ribosomal DNA (rDNA) and 16S sequencing. Two lactobacilli were identified as Lactobacillus oris and Lactobacillus fermentum. In the light of this study, it is observed that, human milk is a source of potential probiotic strains.