Endophytic Bacteria Associated With Solanum Tuberosum (Irish Potato) Roots

Abstract

The aim of this study was to isolate endophytic bacteria from Solanum tuberosum (Irish Potato) roots. Root tubers of healthy irish potato were bought from the market located in Umudike, Abia state. The samples were surfaced sterilized, isolated and plated. The result shows that water washing from surface-sterilized root samples showed no microbial growth on trypic soy agar after incubation at 25^oC. In addition, representative endophytes cultures that were also surface sterilized also failed to grow on trypic Soy agar. This indicates that epiphytic bacteria could not grow after surface sterilization and that any subsequent bacterial isolates were in fact endophytic. The two isolates Pseudomonas sp and Bacillus sp were Gram positive cocci and Gram positive rod-shaped. Morphological and physiological characteristics of the isolates showed that they belonged to the genera Pseudomonas sp and Bacillus sp. The Present study revealed that roots of S tuberosum provided a rich source of endophytic bacteria diversity. Further investigations are required to understand the potential of these endophytes as biocontrol and plant growth promoting agents that may be useful in pharmacological and agricultural fields in future.

TABLE OF CONTENTS

Cover Page                                                                                                                             

Title Page                                                                                                                                i

Declaration                                                                                                                              ii

Certification                                                                                                                            iii

Dedication                                                                                                                              iv

Acknowledgement                                                                                                                  v

Table of Contents                                                                                                                   vi

List of Tables                                                                                                                          viii

Abstract                                                                                                                                  ix

CHAPTER ONE

1.1 Background the Study                                                                                                  1

1.2 Problem Statement                                                                                                           5

1.3 Aim Objectives of the Study                                                                                            5

1.4 Significance of the Study                                                                                                 6

CHAPTER TWO

LITERATURE REVIEW

2.1 General Characteristics of Endophytic bacteria                                                               7

2.2 Distribution of endophytic bacteria in natural habitats                                                    8

2.2.1 Endophytic Endophytic bacteria                                                                                    8

2.3 Isolation of Endophytics Endophytic bacteria                                                                  18

2.3.1 Isolation media                                                                                                              19

2.3.2 Physical or chemical pretreatment method                                                                   19

2.3.3 Other method for selective isolation of endophytic endophytic bacteria                      19

2.4 Identification and classification of endophytic bacteria                                                   20

2.5 Bioactive metabolites from endophytic bacteria                                                              21

2.5.1 Antibiotics                                                                                                                     22

2.5.2 Extracellular enzymes                                                                                                   24

2.5.3 Plant growth promoters                                                                                                 25

2.6 Endophytic bacteria as Biological Control Agents                                                          29

CHAPTER THREE

METHODOLOGY

3.1 Sample Collection                                                                                                             32

3.2 Surface Sterilization and Isolation                                                                                   32

3.2.1 Test for Effectiveness of Surface Sterilization                                                              32

3.3 Selective Isolation of Endophytic Endophytic Bacteria                                                   32

3.4 Biochemical Tests                                                                                                             33

3.4.1 Coagulase Test                                                                                                               33

3.4.2 Catalase Test                                                                                                                  33

3.4.3 Methyle red test                                                                                                             34

3.4.4 Indole test                                                                                                                      34

3.4.5 Oxidase Test                                                                                                                  34

3.4.6 Gram Staining                                                                                                                35

3.4.7 Sugar fermentation test                                                                                                  36

CHAPTER FOUR

RESULTS

4.1 Identification of Bacteria Endophytes                                                                              38

CHAPTER FIVE

DISCUSSION AND CONCLUSION

5.1 Discussion                                                                                                                         41

5.2 Conclusion                                                                                                                        42

References                                                                                                                              43

LIST OF TABLES

Table 2.1 Actinomycete antibiotics for medical applications (Kieser et al 2000)                 20

Table 4.1 showing morphological characteristics of bacteria isolated from potato

(Solanum tuberosum) root                                                                                                      39

Table 4.2 Biochemical Tests Result for isolates of S tuberosum                                           41

Table 4.3 Frequency of Occurrence of Endophytic Bacteria                                                 42