Microbiological Control Of Post-Harvest Fungal Pathogens Of Cocoyam Using Bacillus Species

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