The Effect Of Exopolysaccharides Of Lactic Acid Bacteria On Some Food Borne Pathogens

ABSTRACT

The inhibition of food borne pathogens by exopolysaccharides of lactic Acid Bacteria isolates from Ugba was investigated. Food borne pathogens were isolated from three food types, Rice, beans and soup including Staphylococcus aureus, Escherichia coli, species of Proteus, Pseudomonas, Shigella, Salmonella and Bacillus. The prevalence of these isolates varied with Staphylococcus species being in all foods (100%), Bacillus (56%), Shigella(44.49%), Pseudomonas (33.3%), E.coli (22.2%), Proteus and Salmonella (11.1%) each. Three Lactic Acid Bacteria, L. plantarum, L. casei  and L. fermemtum were isolated from Ugba samples and had Exopolysaccharides yields of 121.67mg/l, 116.67mg/l and 98.33mg/l respectively. The antibacterial activity tests showed limited but significant activity of the EPS in the range of 8.33mm to 15.0mm diameter of inhibitions. Lactobacillus casei EPS had the highest level of inhibition against the isolates ranging from 9.00mm(Bacillus) to 15.0mm (Proteus) while L. plantarum EPS had least activity in the range of 0.00(Bacillus) to 12.67mm (Proteus). Comparatively, the Gram positive isolates were less susceptible to EPS (0.00mm to 11.67mm) than the Gram negative isolates (9.33mm to 15.0mm).There were also variations in the levels of activities of the EPS extracts from the different levels of activities of the EPS extracts from the different LABs from fermented foods like Ugba has potentials as good sources of bioactive metabolites with high utility value especially as supplement if not alternatives to commercial antibiotics.

TABLE OF CONTENTS

Title page ﾿ i ﾿

Dedication ﾿ ii

Acknowledgements ﾿ iii ﾿

Table of Contents ﾿ iv ﾿

Abstract ﾿ v ﾿

CHAPTER ONE

1.0 ﾿ Introduction ﾿ 1

1.1 ﾿ Aim ﾿ 4

1.2 ﾿ Objectives ﾿ 4

CHAPTER TWO

2.0 ﾿ Literature Review ﾿ 5

2.1 ﾿ Ugba

2.2 ﾿ Lactic Acid Bacteria ﾿ 7

2.3 ﾿ Taxonomical Classification of Lactic Acid Bacteria ﾿ 7

2.4 ﾿ Occurrence of Lactic Acid Bacteria in Nature ﾿ 8

2.5 ﾿ Exopolysaccharide ﾿ 8

2.6 ﾿ Exopolysaccharide Producing Bacteria ﾿ 9

2.7 ﾿ Biosynthetic Pathways Leading To Exopolysaccharide Synthesis in Lab ﾿ 11

2.8 ﾿ Classification and Chemical Composition of Exopolysaccharide ﾿ 13

2.8.1 ﾿ Homo-exopolysaccharide ﾿ 14

2.8.2 ﾿ Hetero-exopolysaccharide ﾿ 16

2.9 ﾿ Exopolysaccharide Yields Produced By Lactic Acid Bacteria ﾿ 17

2.10 ﾿ Health Properties of Exopolysaccharide ﾿ 18

2.11 ﾿ Novel Applications of Exopolysaccharides from Lactic Acid Bacteria ﾿ 19

2.12 ﾿ Foodborne Bacterial Pathogens ﾿ 20

2.12.1 ﾿ Salmonella ﾿ 20

2.12.2 ﾿ Staphylococcus aureus ﾿ 20

2.12.3 ﾿ Clostridium botulinum ﾿ 21

2.12.4 ﾿ Shigella ﾿ 21

CHAPTER THREE

3.0 ﾿ Materials and Methods ﾿ 21

3.1 ﾿ Source of Materials ﾿ 21

3.2 ﾿ Media and Sample Preparations ﾿ 21

3.2.1 ﾿ Media Preparation ﾿ 21

3.2.2 ﾿ Sample Preparation ﾿ 22

3.3 ﾿ Isolation of Food Borne Pathogens ﾿ 22

3.4 ﾿ Characterization and Identification of Food Borne Pathogens. ﾿ 23

3.4.1 ﾿ Colony morphology. ﾿ 23

3.4.2 ﾿ Microscopic characteristics ﾿ 23

3.4.3 ﾿ Biochemical Reaction Tests ﾿ 23

3.4.3.1 ﾿ Catalase Test ﾿ 24

3.4.3.2 ﾿ Indole Test ﾿ 24

3.4.3.3 ﾿ Coagulase Test ﾿ 24

3.4.3.4 ﾿ Oxidase Test ﾿ 24

3.4.3.5 ﾿ Motility, Indole, Urease (MIU) ﾿ 25

3.4.4 ﾿ Carbohydrate utilization test ﾿ 25

3.5 ﾿ Isolation of Lab from Ugba ﾿ 26

3.6 ﾿ Extraction of Exopolysaccharide ﾿ 26

CHAPTER FOUR

4.0 ﾿ Results ﾿ 27

CHAPTER FIVE

5.0 ﾿ Discussion, Conclusion and Recommendations ﾿ 35

5.1 ﾿ Discussion ﾿ 35

5.2 ﾿ Recommendation ﾿ 37

5.3 ﾿ Conclusion ﾿ 37

﾿ References ﾿ 38