DROUGHT TOLERANT BACTERIA ASSOCIATED WITH ALOE VERA RHIZOSPHERE SOIL

ABSTRACT

A major environmental problem facing most countries of the world today, regarding agricultural productivity and food availability, is drought. The aim of the study was to isolate and characterize drought tolerant bacteria from aloe vera rhizosphere soil. Soil samples were collected from National Root Crop Research Institute, Umudike. The soil samples were collected from the rhizosphere of aloe vera plant. A total of 12 bacterial isolates were isolated from rhizosphere of aloe vera soil for drought tolerance activity which were identified by different morphological and biochemical characterization. The total bacteria heterotrophic count which ranged from 1.28 x106 Cfu/g to 1.72 x 106 Cfu/g.  The percentage occurrence of the isolates. Bacillus sp 41.7% had the highest percentage occurrence followed by Streptomyces sp 33% while Paenibacillus sp 25% showed the least percentage occurrence. The drought tolerance potential of the isolate determined using an OD reading at 600nm among the different osmotic stresses, all the bacteria attain maximum growth at 0.44MPa stress. Changes in climatic conditions can bring about undesirable environmental conditions, including drought which decrease crop productivity hence the importance of drought resisted microorganisms that are beneficial to plants.

TABLE OF CONTENTS

Title Page                                                                                                                                i

Certification                                                                                                                            ii

Dedication                                                                                                                               iii

Acknowledgements                                                                                                                iv

Table of Contents                                                                                                                   v

Lists of Tables                                                                                                                        viii

List of Figures                                                                                                                         ix

Abstract          

CHAPTER ONE

1.0  Introduction                                                                                                                1

1.1 Aim and Objectives                                                                                                          3

1.2 Objectives                                                                                                                         3

CHAPTER TWO

2.0  Literature Review                                                                                                                   4

2.1 Actinomycetes                                                                                                                  7

2.1 Taxanomy                                                                                                                         10

2.2 Bioactive Agents in Actinomycetes                                                                                 12

2.2.1 Antibiotics                                                                                                                     12

2.2.2 Antifungals                                                                                                                    12

2.3 Plant Growth Bioactive Molecules.                                                                                 13

2.3.1 Indole Acetic Acid                                                                                                         13

2.3.2 Hydrogen Cyanide                                                                                                         14

2.4 Soil Bacteria Community Responses to Drought                                                             15

2.5 Potential Causes of Soil Community Trends under Drought                                           17

2.6 Causes for Bacterial Community Trends in Drought-Stressed Roots                            19

CHAPTER THREE             

3.0 Materials and Methods                                                                                                     21

3.1 Sample Collection                                                                                                                                                            21

3.2 Sterilization of Materials                                                                                                              21

.3.3 Pre-Treatment of Soil Samples                                                                                        21

3.4 Media Used                                                                                                                       21

3.5 Media Preparation                                                                                                            21       

3.6 Isolation and Selection of Bacteria                                                                                   22

.3.6.1 Identification                                                                                                                22

3.6.2 Sub-culturing                                                                                                                 23

3.6.3 Gram Staining                                                                                                               23

3.7 Biochemical Test                                                                                                              23

3.7.1 Starch hydrolysis test                                                                                                     23

3.7.2 Hydrogen sulfide test.                                                                                                    24

3.7.3 Gelatin hydrolysis                                                                                                          24

3.7.4 Catalase test                                                                                                                   25

3.7.5 Oxidase test                                                                                                                   25

3.7.6 Carbohydrate fermentation test                                                                                     25

3.7.7 Test for casein hydrolysis                                                                                              26

 3.7.8 Drought Tolerance Abilities of Bacterial Isolates                                                        26

CHAPTER FOUR

4.0 Results                                                                                                                              27

CHAPTER FIVE

5.0 DISCUSSION, CONCLUSION AND RECOMMENDATION                                    32

5.1 Discussion                                                                                                                         32

5.2 Conclusion                                                                                                                        36

5.3 Recommendation                                                                                                             36

LIST OF TABLES

Table                     Title                                                                Page

4.1 Total Heterotrophic Bacterial Load (cfu/g) of Aloe Vera rhizosphere                                    28

4.2 Colonial description and biochemical characteristics of isolated bacteria                       29

4.3 Percentage occurrence of isolates                                                   30

4.4 Drought Tolerance potential of the isolate determined using an OD reading at 600nm        31

CHAPTER ONE

1.0  INTRODUCTION

A major environmental problem facing most countries of the world today, regarding agricultural productivity and food availability, is drought. Drought has been a subject of concern as it has led to reduced plant growth and yield. It is therefore very important to seek means of reducing this menace, to increase food availability and sustain food security. At present, strategies like breeding and genetic modifications are being used to manage this problem (Langridge and Reynolds 2015; Maazou et al., 2016). Agricultural practices including soil amelioration and mulching have also been used (Jongdee et al., 2012). However, these strategies are not very efficient as they are not only time consuming but labor and cost intensive (Ashraf, 2014; Eisenstein, 2016).

 Often times, some desirable plants traits in the host plant gene pool can be unintentionally lost in the process of breeding (Philippot et al., 2013). Moreover, plant breeding transfers benefit to single host specie and not to other crop systems, as it is usually difficult to identify the genetic component responsible for this improvement (Coleman-Derr and Tringe, 2014). The drawbacks mentioned above have made these technologies highly unreliable, leading to a quest for better and more efficient means to tackle this problem. In recent times, the use of beneficial microbial species with plant growth promoting capabilities to relieve plants of the adverse effects of drought has become more relevant in agriculture (Babalola and Glick, 2012). Bacteria are important soil components, able to form mutualistic and beneficial associations with most plants (Ndeddy Aka and Babalola, 2016). Symbiotic bacteria are capable of conferring stress tolerance to a wide variety of plant hosts through phytohormonal modifications, production of exopolysaccharides, accumulation of osmolytes and acting as defense against reactive oxygen species (Zhang et al., 2012; Coleman-Derr and Tringe, 2015).

These bacteria are also able to synthesize antibiotic substances, fix atmospheric nitrogen, produce soluble iron compounds (siderophore), and solubilize inorganic phosphates (Babalola, 2012; Adegboye and Babalola, 2013). In addition, they serve as plant growth regulators by producing the phytohormones indole-acetic acid (IAA), 1-aminocyclopropane-1-carboxylic acid (ACC), cytokinins and gibberellins (GA) (Khantsi et al., 2013; Ndeddy Aka and Babalola, 2017). These outstanding properties of the plant growth promoting bacteria (PGPB) facilitate the efficient stimulation of plant growth during unfavorable environmental conditions like drought (Yandigeri et al., 2012). Several studies have revealed the successful application of isolated PGPB on drought stress improvement in plants (Figueiredo et al., 2008; Yandigeri et al., 2012; Gusain et al., 2015).

 However, most of these studies have concentrated on certain groups of bacteria species, mostly Pseudomonas and Bacillus. The use of actinomycetes species to enhance stress tolerance in plants have received very little attention over the years. Actinomycetes, found mostly in soils, are widely known for their antibiotic and bioactive secondary metabolites production as well as their outstanding ability to survive in unfavorable environments (Adegboye and Babalola, 2013; Adegboye and Babaloa, 2015; Passari et al., 2015). Their ability to produce certain plant growth promoting properties has also been identified, but with little information on the extent of the properties produced (Ali et al., 2014; Sreevidya et al., 2016).

1.1 AIM AND OBJECTIVES

The aim of this study is isolation and characterization of drought tolerant bacteria from aloe vera rhizosphere soil.

1.2 OBJECTIVES

1.     Isolate drought tolerant bacteria from aloe vera rhizosphere soil.

2.     Characterize drought tolerant bacteria from aloe vera rhizosphere soil.

3.     Determine the drought tolerance level of bacteria from aloe vera rhizosphere soil.

Buyers has the right to create dispute within seven (7) days of purchase for 100% refund request when you experience issue with the file received. 

Dispute can only be created when you receive a corrupt file, a wrong file or irregularities in the table of contents and content of the file you received. 

ProjectShelve.com shall either provide the appropriate file within 48hrs or send refund excluding your bank transaction charges. Term and Conditions are applied.

Buyers are expected to confirm that the material you are paying for is available on our website ProjectShelve.com and you have selected the right material, you have also gone through the preliminary pages and it interests you before payment. DO NOT MAKE BANK PAYMENT IF YOUR TOPIC IS NOT ON THE WEBSITE.

In case of payment for a material not available on ProjectShelve.com, the management of ProjectShelve.com has the right to keep your money until you send a topic that is available on our website within 48 hours.

You cannot change topic after receiving material of the topic you ordered and paid for.