Lactobacillus rhamnosus ATCC RW-9595M이 생산하는 균체외다당류의 이화학적, 생리학적 특성에 관한 연구 = Characterization of Physicochemical Properties and Physiological Functionalities of Exopolysaccharides Produced by Lactobacillus rhamnosus RW-9595M

국문 초록 (Abstract)

본 연구에서는 Lactobacillus rhamnosus RW-9595M이 생산하는 EPS의 생산 경향을 조사하였고 이를 각각 cell bound EPS (b-EPS)와 released EPS (r-EPS)로 분리, 이들의 특징과 더불어 항암과 cholera toxin의 중화 효과 그리고 EPS생산 최적 조건을 조사하였다. 이 균종은 대수기에서 전체 EPS 생산이 증가하며 배양시간에 따라 b-EPS와 r-EPS의 비율은 각각 다르게 나타났다. 분리한 5 mg/ml의 r-EPS와 b-EPS를 cancer cell과 cholera toxin에 적용하였을 때 대조구에 비해 HT-29, HeLa cell line에서 모두 성장 저해 효과를 보였고 r-EPS의 효과가 더 높은 것으로 나타났다. ELISA법을 이용한 toxin 중화 효과에서도 cholera toxin에 대해 r-EPS의 중화 효과가 b-EPS보다 유의적으로 높은 것으로 조사되었다. 이와 더불어 L. rhamnosus RW-9595M이 생산하는 EPS는 pH 5.5, 37 ℃에서 가장 많이 생산되며 이 조건에 0.5% 이상의 WPC를 첨가하였을 때 그 수율이 가장 높게 나타나는 것으로 조사되었다.

목차 (Table of Contents)

• TABLE OF CONTENTS
• Page
• ABSTRACT ⅰ
• ACKNOWLEDGEMENT ⅲ
• TABLE OF CONTENTS ⅵ
• LIST OF TABLES ⅶ
• LIST OF FIGURES ⅷ
• LIST OF ABBREVIATIONS ⅹ
• 1. INTRODUCTION 1
• 2. LITERATURE REVIEW 4
• 2.1 Exopolysaccharides from microbial origin 4
• 2.1.1 Exopolysaccharides produced by lactic acid bacteria 4
• 2.2 Classification of exopolysaccharides from lactic acid bacteria 6
• 2.3 Biosynthetic pathways leading to EPS synthesis in LAB 8
• 2.4 Relationship between glycolysis and exopolysaccharide biosynthesis 14
• 2.5 Physiological characteristics of exopolysaccharides from lactic acid
• Bacteria 16
• 2.6 Exopolysaccharides yields from lactic acid bacteria 18
• 2.7 Enhancement of exopolysaccharides yields 20
• 2.8 Physicochemical characteristics of exopolysaccharides 24
• 2.9 Functional characteristics of exopolysaccharides 26
• 2.10 Application of exopolysaccharides from lactic acid bacteria 27
• 3. The characterizations and production patterns of two different EPS produced by Lactobacillus rhamnosus RW-9595M32
• 3.1 Materials and methods 30
• 3.1.1 Bacterial strains 30
• 3.1.2 Culture conditions for EPS production 30
• 3.1.3 Sampling and enumeration of bacterial cells 31
• 3.1.4 Isolation and purification of two types of exopolysaccharides 31
• 3.1.4.1 Extraction of released exopolysaccharides (r-EPS) 31
• 3.1.4.2 Extraction of cell bound exopolysaccharides (b-EPS) 32
• 3.1.4.3 Quantification of exopolysaccharides 33
• 3.1.5 Molecular mass determination 34
• 3.1.6 Apparent and intrinsic viscosity of exopolysaccharides 34
• 3.1.7 Monosaccharide composition of isolated EPS 35
• 3.2 Results and discussion 36
• 3.2.1 Localization of exopolysaccharides 36
• 3.2.2 Determination of molecular weight of two types of exopolysaccharides 39
• 3.2.3 The relationship of molecular weight and viscosity 43
• 3.2.4 EPS monosaccharide composition 46
• 4. Improvement EPS production under optimal culture condition 48
• 4.1 Materials and methods 48
• 4.1.1 Effects of pH on cell growth and EPS production 48
• 4.1.2 Effects of temperature on cell growth and EPS pr