Title Page

ABSTRACT

Contents

Chapter 1. Introduction 11

1.1. Research Background 11

Chapter 2. Experimental section and methods 13

2.1. Fish-Collagen Peptide Preparation 13

2.2. Animal Testing and Diet Management 16

2.3. Gathering Fecal and Blood Samples 16

2.4. Fecal Endotoxin Measurement 16

2.5. Cell Culture Conditions 17

2.6. ELISA Assay 17

2.7. Gut Microbiome Analysis 18

Chapter 3. Results and Discussion 20

3.1. Results 20

3.1.1. Valuable Peptide Screening for Disease Treatment Based on Gut Microbiota Composition 20

3.1.2. Physiological Alterations Depending on the Presence or Absence of Collagen Peptide Intake in an Obese Mouse Model Fed a High-Fat Diet. 24

3.1.3. Members of Gut Microbiome Community Altered by Collagen Peptide Consumption in an Obese Mouse Model induced by a High-Fat Diet. 30

3.1.4. The Alteration of the Gut Microbiota induced by Collagen Peptide Consumption Leads to Changes in the Metabolic Pathways Mediated by the Microbiota. 36

3.2. Discussion 41

Reference 44

국문초록 48

Table 2.1. The composition of amino acids of collagen peptide. 14

Table 2.2. Molecular weight of collagen peptide. 15

Table 2.3. List of Primers used for Sequencing the V3V4 region of 16S rRNA. 19

Figure 3.1. Identification of peptides that exert a considerable effect on the gut microbiome. 22

Figure 3.2. Changes in F/B ratio over time after collagen peptide administration. 23

Figure 3.3. The scheme of the animal experiment and the comparison of physiological levels among groups. 26

Figure 3.4. Comparison of pro-inflammatory cytokine levels among groups. 28

Figure 3.5. The results of the blood-biochemical analysis. 29

Figure 3.6. Comparison of gut microbial community composition and diversity among three groups. 32

Figure 3.7. LEfSe bar plot (HFD + vehicle vs HFD + collagen). 33

Figure 3.8. Comparison of the relative abundance of specific OTUs that exhibited significant differences in LEfSe between the groups. 34

Figure 3.9. A box plot illustrating the differences in OTU abundances between the two groups. 35

Figure 3.10. Heatmap visualization of significantly distinct functional profiles inferred by PICRUSt2 based on the presence or absence of collagen peptide. 37

Figure 3.11. The anticipated functional profile variances between HFD + collagen and HFD + vehicle mice using PICRUSt2. 38

Figure 3.12. Boxplots depicting the relative abundance in 27 pathways related to obesity. 40