ABSTRACT

Microbial control of post harvest fungal pathogen of cocoyam using Bacillus species was investigated. Fungi were isolated from rot infested cocoyam corms and identified with varying occurrences levels including Aspergillus (100%), Penicillum (80%), Rhizopus (60%), yeast (100% and Fusarium oxysporium (60%). Pathogencity test implicated three fungi specie as pathogens with  varying levels of demonstrated pathogencity as show by percentage rots of Aspergillus (59%) Fusarium (48.15%) and Penicillum (45%) the inoculate of in-vitro antifungal tests reveals varying levels of antifungal activity with inhibition zones of Bacillus thuruingensis 14.3mm, Bacillus subtilis 13.3mm, Bacillus megaterium 11.0mm and Bacillus cereus 12.7mm. In vitro test recorded percentage inhibitions of 57%. The higher activity was recorded against Fusarium (57%) by Bacillus thuruingensis while the test inhibition was recorded against Aspergillus (41%) by Bacillus megaterium. The different Bacillus species exhibited varying levels of inhibition activity against the cocoyam fungi pathogen. Comparatively Fusarium was the most inhibited with a mean inhibition of 53% while Penicillum was the least inhibited (49%) of all the fungi pathogens. It was observed that the Bacillus growth has potentials for the use as bio-control agent, to protect cocoyam corms after harvest. But there is need for a further study regarding their mode of application in concentrate terms.

TABLE OF CONTENTS

S/N             Titles        Page

Title Page   i

Certification iii

Dedication iv

Acknowledgement v

Table of Contents vi

List of Tables vii

Abstract ix

CHAPTER ONE

1.1 Introduction 1

1.2 Aim of the Study 2

1.3 Objectives of Study 2

CHAPTER TWO

2.1 Literature Review 3

2.1 Brief Description of Cocoyam 3

2.2 Nutritional Benefits of Cocoyam 3

2.3 Health Benefits 4

2.3.1 Cancer Prevention 4

2.3.2 Reduce Symptoms of Rheumatoid Arthritis 4

2.3.3 Blood Pressure and Heart Health 5

2.3.4 Immune System Health 5

2.3.5 Cramps 5

2.4 Scenario of Food Spoilage Worldwide (e.g. Cocoyam) 6

2.5 Food Spoilage Microorganisms 9

2.5.1 Yeasts 9

2.5.2 Molds 10

2.5.3 Bacteria 12

2.6 Isolation, Identification and Pathogenicity of Fungi Associated with 

Cocoyam (Colocasia esculenta) Spoilage 14

2.7 Fungi Associated with the Spoilage of Post-Harvest Cocoyam 

(Colocasia esculenta) Sold in Major Markets in Awka, Nigeria 15

2.8 Control of Rot and Spoilage of Agricultural Products 17

2.8.1 Good Agronomic Practices, Field Sanitation and Store Hygiene 17

2.8.2 Thermal and Physical Control 19

2.8.3 Biological Control of Rot Organisms 20

2.8.4 Chemical Control of Rots and their Causal Agents in Postharvest Produce 21

2.9 Antibiotics Activities of Bacillus subtilis 23

CHAPTER THREE

3.1 Materials 25

3.1.1 Source/Collection of Samples 25

3.1.2 Materials and Media Used 25

3.1.3 Sterilization of Materials 25

3.2 Method 26

3.2.1 Isolation of Bacillus from Agricultural Soil 26

3.3 Isolation of Fungi from Spoilt Cocoyam 26

3.3.1 Processing of Samples 26

3.3.2 Preparation of sample and inoculation of samples 26

3.3.3 Isolation of Fungi 26

3.3.4 Subculturing/Purification and Identification of Test Fungi Pathogens 27

3.4 Identification of Fungi Isolates 27

3.4.1 Wet Preparation 27

3.4.2 Colonial Morphology 27

3.5 Pathogenecity Test for Fungi Isolate Cocoyam Pathogens 27

3.6 In-Vitro Antifungal Activity of Bacillus Isolates against Cocoyam Pathogens 28

CHAPTER FOUR

4.1 Results 30

CHAPTER FIVE

5.1 Discussion, Conclusion and Recommendation 36

5.1 Discussion 36

5.2 Conclusion 37

5.3 Recommendation 37

References