DETERMINATION OF EXOPOLYSACCHARIDES FROM LACTIC ACID BACTERIA ISOLATED FROM FERMENTED FOODS

ABSTRACT

Exopolysaccharides were determined from lactic acid bacteria isolated from fermented foods. Foofoo, Ogiri, Ugba, and Yoghurt were the fermented foods used. Five lactic acid bacteria including species of Lactobacillus, Streptococcus, Bacillus, Micrococcus and Leuconostoc. The occurrence of the isolates were Lactobacillus (78%), Leuconostoc (50%), Micrococcus (66.7%), Streptococcus (50%) and Bacillus (66.7%). The distribution of the isolates in the fermented foods vary significantly. Tests on EPS production shsow that the quanitity of EPS produced by the different lactic acid bacteria vary between the organisms. The yield was highest 486.67 mg/l from Lactobacillus, and least 130.0 mg/l in Leuconostoc while Streptococcus, Micrococcus and Bacillus yielded 413.3 mg/l, 133.3mg/l, 320.0 mg/l respectively. Test on optimization of conditions for maximum EPS production show that temperature, pH and fermentation time affected the production of EPS but the optimum conditions show that fermentation at pH 5.0 at 40°C for 96 hours yielded the best results in all the test lactic acid bacteria. Although variations were needed in the preferences of the isolates which includes Bacillus, Streptococcus, and Lactobacillus were used in the optimization test which gave the same result irrespective of the organisms involved. It was recorded that EPS production should be conducted at the above found optimum conditions for maximum yield.   

TABLE OF CONTENTS 

Title page ﾿     i

Certification ﾿     ii

Dedication ﾿     iii

Acknowledgement ﾿     iv

Table of Contents ﾿     v

List of Tables ﾿     vii

List of Figures ﾿     viii

Abstract ﾿      ix

CHAPTER ONE 

1.1 ﾿ Introduction ﾿      1

1.2 Objective of study ﾿      2

CHAPTER TWO

2.0    Literature Review ﾿      3

2.1    Exopolysaccharides ﾿      3

2.1.1 Exopolysaccharides from Lactic acid bacteria ﾿      3

2.1.2 Application of Exopolysaccharides in foods ﾿      4

2.2.   Lactic acid bacteria ﾿      5

2.2.1 Application  of Lactic acid bacteria ﾿      5

2.3    Fermented foods ﾿      6

2.3.1 Purpose and benefits of food fermentation ﾿      7

2.3.2 Nutritional benefits of food fermentation ﾿      7

CHAPTER THREE

3.0   Materials and methods ﾿      9

3.1   Sources of materials ﾿      9

3.2   Sample preparation and media preparation ﾿      9

3.2.1 Preparation of sample ﾿      9

3.2.2 Media preparation ﾿      9

3.2.3 Preparation of MRS media ﾿     10

3.3    Isolation of lactic acid bacteria ﾿     10

3.4    Identification of isolates ﾿     11

3.5    Screening for exopolysaccharide Production ﾿     11

3.6    Extraction of exopolysaccharide            ﾿     12

3.7    Optimization of EPS production ﾿     12

CHAPTER FOUR

Results ﾿     14

CHAPTER FIVE

Discussion ﾿     24

Conclusion ﾿     26

References ﾿    26