ABSTRACT

Antimicrobial properties of probiotic bacteria from different sources were studied. Lactic Acid Bacteria were isolated from three different fermented food sources, Ogi, Ugba and Ogiri and were tested for their respective probiotic properties after which their microbial activities were tested against three pathogenic organisms, E. coli, Staphlylococus aureus and Candida spp. Results obtained showed the isolation of four Lactobacillus species, Lactobacillus plantarum, L.casei, L. fermentum and L. acidophilus with different occurrences levels in the fermented foods. Lactobactllus plantarum had 100% occurrence, L. casei (66.7%), L. fermentum and L. acidophilus had 33.3% each. The LAB isolates were confirmed to be probiotics following their successful but varied responses showing their ability to produce gas from glucose, salt and bile tolerance as well as growing in the presence of phenol. Test for antimicrobial ability of the probiotics show activities against the pathogens with mean inhibition diameters in the range of 10.67mm to 14.67mm against E. coli, 9.33mm to 10.67mm against Staphylococcus aureus and 12.33mm to 14.67mm against Candida albicans. Comparatively, Lactobacillus plantarum isolate from “ogiri” had the least antimicrobial effects. Also Candida albicans was the most susceptible to the probiotics while Staphylococcus aureus had the least resistance. It was observed that the LAB isolates were probiotics and demonstrated significant antimicrobial properties.

TABLE OF CONTENTS

Title page i

Certification ii

Dedication iii

Acknowledgements iv

Table of contents v

List of Tables vii

List of Figures viii

Abstract ix

CHAPTER ONE

1.0 Introduction 1

1.1 Description of some local food condiments 4

1.1.1 Ogiri (Ricinus communis) 4

1.1.2 Ugba (Pentaclethra macrophylla, Benth) 5

1.1.3 Ogi (Cereal Starch L.) 5

1.2 Aims and objectives 6

CHAPTER TWO

LITERATURE REVIEW

2.1 History and definition of probiotics 7

2.1.2 Classes of microorganisms used as probiotics 8

2.1.3 Lactobacillus 10

2.1.4 Bifidobacterium 10

2.1.5 Bacillus 11

2.1.6 Enterococcus 12

2.1.7    Saccharomyces 13

2.1.8 Criteria for the selection of probiotics 14

2.2 Applications and relevance of probiotics 17

2.2.1 Human health 17

2.2.2 Agriculture 18

2.2.3 Pharmaceutical industry 19

2.3 Lactic acid bacteria (lab) 19

2.3.1 Antimicrobial peptide Bacteriocin produced by lactic acid bacteria 19

2.3.2 Bacteriocin produced by Streptococcus spp. 21

2.3.3 Bacteriocins produced by Enterococcus faecium 22

2.3.4 Bacteriocins produced by Lactobacillus plantarum 23

2.4 Review of food sources used 24

2.4.1 Ogi (Cereal Starch L.) 24

2.4.2 Ogiri (Ricinus communis) 25

2.4.3 Ugba (Pentaclethramacrophylla, Benth) 27

CHAPTER THREE

MATERIALS AND METHODS

3.1 Source of materials 29

3.2 Media preparation 29

3.3 Isolation of lactic acid bacteria 29

3.4 Characteristics of lab isolates 30

3.5 Test for probiotic activity of LAB isolates 35

3.5.1 Salt Tolerance Test 35

3.5.2 Phenol Tolerance Test 35

3.5.3 Bile Salt Tolerance Test 36

3.5.4 Temperature Tolerance 36

3.6 Antimicrobial activity test on probiotics 36

CHAPTER FOUR

4.0 Results 38

CHAPTER FIVE

DISCUSSION, CONCLUSION AND RECOMMENDATION

5.1 Discussion 44

5.2 Conclusion 45

5.3 Recommendation` 45

REFERENCES