Effect Of Carbon Sources On The Growth Of Antimicrobial Producing Bacillus Species In Citrullus Vulgaris

ABSTRACT

The effect of carbon sources on the growth of antimicrobial producing Bacillus species in Citrullus vulgaris (Ogiri) was studied in this research. A total of 11 antimicrobial producing strains were isolated of which 8 were identified through morphological and biochemical tests were of the genus Bacillus. The isolates were identified as B. subtilis, B. megaterium and B. firmus. Isolate K6 identified as B. subtilis produced the highest recorded zone of inhibition (22 mm) when all the isolates were grown in culture media seeded with the test organism S. aureus. The effect of different carbon sources (glucose, starch and sucrose) on the Bacillus isolates were investigated individually. It was observed that optimum growth was achieved when all the Bacillus isolates were grown on media having starch (5 and 10% concentration) and sucrose (5 and 10% concentration) respectively. Weak to moderate growths were observed in the presence of glucose with evident growth seen more at 10% concentration and as such was deduced to be less effective for growth of the Bacillus species isolated from Citrullus vulgaris. Although all isolates grew well in the presence of starch, isolates K2 and K5 identified as B. megaterium were not able to grow with starch as a carbon source but could grow in the presence of glucose and sucrose. This could be attributed to their inability to hydrolyze starch. Isolates K1. K3, K4, K6, K7 and K8 could all grow in the presence of all the tested carbon sources. From the experiment, it was observed that maximum growth was with starch and sucrose for 72 hours at 37oC.  

TABLE OF CONTENTS

Title page ﾿ i

Certification ﾿ ii

Dedication ﾿ iii

Acknowledgments ﾿ iv

Table of contents ﾿ v

List of tables ﾿ viii

Abstract ﾿ ix

CHAPTER ONE

INTRODUCTION ﾿ 1

1.1 ﾿ Aim of the Study ﾿ 3

1.2. ﾿ Objectives of the Study ﾿ 3

CHAPTER TWO

LITERATURE REVIEW ﾿ 4

2.1 ﾿ Fermentation ﾿ 4

2.1.1 ﾿ Importance of Fermentation ﾿ 5

2.2 ﾿ Fermented Foods ﾿ 7

2.3 ﾿ Traditionally Fermented Foods in Nigeria ﾿ 8 ﾿

2.4 ﾿ Citrullus vulgaris (Melon) ﾿ 11

2.4.1 ﾿ Description of the Seeds ﾿ 11

2.4.2 ﾿ Composition of the Seeds ﾿ 11

2.4.3 ﾿ Importance of Citrullus vulgaris ﾿ 11

2.5 ﾿ Ogiri ﾿ 12

2.5.1 ﾿ Production of Ogiri ﾿ 12

2.5.2 ﾿ Microbiology of Ogiri ﾿ 13

2.6 ﾿ Bacillaceae ﾿ 14

2.6.1 ﾿ History of Genus Bacillus ﾿ 14

2.6.2 ﾿ Genus Bacillus ﾿ 15

2.6.3 ﾿ Bacillus as a Source of Antimicrobial Compounds ﾿ 17

2.6.3.1 ﾿ Ribosomal Peptide Antibiotics  ﾿ 18

2.6.3.2 ﾿ Non-ribosomal Peptide Antibiotics  ﾿ 19

2.7 ﾿ Effect of Different Carbon Sources on the Growth of Antimicrobial Producing Microorganisms ﾿ 21

CHAPTER THREE

MATERIALS AND METHODS ﾿ 22

3.1 ﾿ Sample Collection ﾿ 22

3.2 ﾿ Isolation of Antimicrobial Producing Organisms from Ogiri Samples ﾿ 22

3.3 ﾿ Characterization and Identification of Antibiotic Producing Bacilli from Ogiri ﾿ 23

3.3.1 ﾿ Biochemical Analysis of the Isolates ﾿ 23

3.3.1.1 ﾿ Gram Staining ﾿ 23

3.3.1.2 ﾿ Catalase Test ﾿ 24

3.3.1.3 Spore Formation Test ﾿ 24

3.3.1.4 ﾿ Methyl Red Vogues Proskauer (MR-VP) Test ﾿ 25

3.4.1.5 ﾿ Oxidase Test ﾿ 26

3.4.1.7 ﾿ Citrate Test ﾿ 26

3.4.1.8 ﾿ Starch Hydrolysis Test ﾿ 26

3.4.1.9 ﾿ Carbohydrate Fermentation Test ﾿ 27

3.5 ﾿ Effect of Different Carbon Sources on the Growth of Antimicrobial Producing Bacillus Species ﾿ 27

CHAPTER FOUR

RESULTS ﾿ 28

CHAPTER FIVE

DISCUSSION AND CONCLUSION ﾿ 32

5.1 ﾿ Discussion ﾿ 32

5.2 ﾿ Conclusion ﾿ 32

References ﾿ 35