Antagonistic Effects Of Bacillus Megaterium Isolated From Rhizosphere Of Tumeric Plants On Cocoyam Fungal Pathogens

ABSTRACT

Cocoyam and other related tuber crops are susceptible to infection by various species of fungi, at all stages of growth and also during storage of tubers. Tuber rot is a major factor limiting the post-harvest life of cocoyam. Sixteen (16) spoilt cocoyam samples were purchased from Ahiaeke market, Abia State. Fresh and healthy cocoyam cormels and cormels showing no symptoms of rot were also obtained for pathogenicity testing. The points of advancement of rot were inoculated on a solidified Sabouraud Dextrose Agar (SDA) agar. Four (4) different fungal isolates were obtained from rotten cocoyams. The isolates included Aspergillus niger, Sclerotium rolfsii, Fusarium solcmi, and Penicillium which were implicated in the rots. Sclerotium rolfsii and Fusarium solani had the highest frequency of occurrence 56.3% and 37.5% respectively followed by Aspergillus niger and Penicillium species with 31.2% and 18.7% frequency of occurrence. In the pathogenicity testing, species of Sclerotium rolfsii and Fusarium solani were very pathogenic while, Aspergillus niger and Penicillium was mildly pathogenic, Sclerotia rolfsii caused a rot severity of 69.34% on the sample with Fusarium solani following it closely with a rot severity of 43.56% Aspergillus niger and Penicillium recorded 27.2% and 14.8% rot respectively. The inhibitory zones produced by the Bacillus species were ranged from 12mm to 16mm in diameter. Four isolates showed inhibitory effect on the pathogens. Bacillus megaterium exhibited the highest inhibition of 16mm and 12mm against Sclerotium rolfsii and Aspergillus niger. Bacillus subtilis and Bacillus licheniformis recorded inhibition zone of 13mm and 15mm respectively against Penicillium species and Aspergillus niger. Fusarium solani was however only susceptible to Bacillus subtilis with a clear zone of 12mm. From the results obtained in this study, it was revealed that Bacillus species possess potential inhibitory activity against rot-inducing fungi of cocoyam.

TABLE OF CONTENTS

S/N ﾿ TITLES ﾿ PAGES

﾿ Declaration ﾿       i 

﾿ Certification ﾿        ii   

﾿ Dedication ﾿ iii

﾿ Acknowledgement ﾿ iv

﾿ Table of Contents ﾿ vi

﾿ List of Tables ﾿ viii

﾿ List of Figures ﾿ ix

﾿ Abstract ﾿ x

﾿ CHAPTER ONE ﾿

1.0 ﾿ Introduction ﾿ 1

1.2 ﾿ Aims and objectives ﾿         7

﾿ CHAPTER TWO ﾿

2.0 ﾿ Literature review ﾿ 8

2.1 ﾿ The importance of cocoyam world wide ﾿ 14

2.2 ﾿ Bacterial as Biological Control Agents ﾿ 15

2.3 ﾿ Antifungal Antibiotics of Bacillus Species ﾿ 19

2.4 ﾿ Diseases of cocoyam ﾿ 20

2.5 ﾿ Root Rot Diseases ﾿ 21

2.6 ﾿ Symptoms and infection of cocoyam diseases ﾿ 22

2.7 ﾿ Management of Fungal Diseases ﾿ 23

2.7.1 ﾿ Biological control of fungal diseases ﾿ 23

3.0 ﾿ CHAPTER THREE ﾿

3.1 ﾿ Sample collection ﾿ 25

3.2 ﾿ Media Preparation ﾿

3.3 ﾿ Isolation of Bacillus Species ﾿ 25

3.4 ﾿ Gram Staining ﾿ 26

3.5 ﾿ Biochemical Tests ﾿ 27

3.5.1 ﾿ Catalase test ﾿ 27

3.5.2 ﾿ Methyl red test ﾿ 27

3.5.3 ﾿ Voges-Proskeur Test ﾿ 27

3.5.4 ﾿ Indole Test ﾿ 28

3.5.5 ﾿ Citrate Utilization Test ﾿ 28

3.5.6 ﾿ Hydrogen Sulphide (H2S) Production Test ﾿ 28

3.5.7 ﾿ Starch Hydrolysis ﾿ 29

3.6 ﾿ Isolation Of Fungal Species From Rotten Yam Tubers ﾿ 29

3.7 ﾿ Identification Of Fungal Isolates ﾿ 30

3.8

﾿ Pathogenicity Test ﾿       30

3.9 ﾿ In Vitro Antifungal Testing ﾿ 31

4.0 ﾿ Result ﾿ 32

5.0 ﾿ Discussion and Conclusion ﾿ 38

5.1 ﾿ Conclusion ﾿ 41

﾿ References¬ ﾿ 42