ABSTRACT

Lactic Acid Bacteria (LAB) as probiotic organisms can be sourced from fermented diary and vegetable products. The problem in Nigeria is their affordability to the greater populace, as the common sources are relatively expensive. The study was aimed at identifying the probiotic LAB and screening their probiotic activity involved in a low cost meal which is locally fermented maize (Akamu). This LAB predominates the microflora of fermented products. They produce metabolites that inhibit the growth of food borne pathogen and are beneficial to the GIT. Isolation and identification of LAB from fermented maize (akamu) was evaluated based on the biochemical characteristics and carbohydrate fermentative pattern. The four (4) isolates of lactic acid bacteria are Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus casie and Enterococcus faecium. The lactic acid bacteria (LAB) strains were tested for their probiotic activity against four test pathogens; Escherichia coli, Salmonella typhimurium, Staphylococcus aureus, and Klebsiella species. Their resistance to acid and bile was determined. Their optimum antimicrobial activity was judged by their different zones of inhibition. There was significant differences between the samples at P<0.05. Lactobacillus plantarum was significantly higher at (21.67±0.58) for Salmonella followed by Lactobacillus acidophilus. The test LAB demonstrated efficient probiotic properties by inhibiting the test pathogens, tolerating acid at pH 3.0 and withstanding 0.3% bile concentration. The results revealed that akamu is a rich source of probiotic LAB and thus can be recommended as food.

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 Probiotics 1

1.2 Prebiotics 2

1.3 Synbiotics 3

1.4 Aim and Objectives of the study 4

CHAPTER TWO

2.0 Literature Review 5

2.1 Lactic Acid Bacteria 5

2.2 Lactobacillus bacteria 6

2.3 Enterococcus 9

2.4 Probiotic Potentials of Lactic Acid Bacteria Isolated from Locally 

Fermented Maize 11

2.4.1 pH and Organic Acid Production 12

2.4.2 Acid and Bile Tolerance 13

2.4.3 Stimulation of the Immune System 14

2.4.4 Adhesion to Intestine Mucus Layer and Epithahial Cells of Human GIT 15

2.4.5 Resistance of Antibiotics 16

CHAPTER THREE

MATERIALS AND METHODS

3.1 Collection of Akamu Samples 17

3.2 Test Organisms 17

3.3 Isolation of Lactic Acid Bacteria from Akamu 17

3.4 Identification of Laboratory Isolates 18

3.4.1 Gram Staining 18

3.5 Biochemical Test 18

3.5.1 Catalase Test 18

3.5.2 Oxidase Test 19

3.6 Sugar Utilization Test 19

3.7 Probiotic Activities of the Isolates 19

3.7.1 Antimicrobial Activities 19

3.7.2 Acid Tolerance 20

3.7.3 Bile Tolerance 20

CHAPTER FOUR

Result 22

CHAPTER FIVE

DISCUSSION AND CONCLUSION

5.1 Discussion 30

5.2 Conclusion 35

REFERENCES