ISOLATION, CHARACTERIZATION AND IDENTIFICATION OF FUNGAL PATHOGENS OF PINEAPPLE FRUITS

ABSTRACT

Fungal phyto-pathogen of pineapple plants were investigated. Fungal isolates from pre-harvest and post-harvest of pineapple plants were characterized and identified. Those isolated from the post-harvest periods were characterized and identified as Saccharomyces cerevisiae, Saccharomyces fragilis, Debaroyomyces spp, Geotricum candidium, Fusarium spp, Aspergillus glaucus, Saccharomyces roiixii and Pichia species.Saccharomyces cerevisiae had the highest rate of occurrence among the isolated fungi,followed by Saccharomyces roiixii, Saccharomyces fragilis, Pichia spp, Geotricum candidium, while Debaroyomyces spp, Aspergillus glaucus and Fusarium spp were the least predominant. While in the pre-harvest fruits no organisms were isolated and identified, but the remarkable observation was that when re-inoculated with the isolates from the spoilt pineapple fruits into which they were incubated at 28oc for 7 days, it was found that the same organisms found in the post-harvest pineapple fruits were responsible for the spoilage of the fruits. The increase load were found to be more in the pre-harvest fruits when reisolated. The microbial load difference between the pre-harvest fruits and post-harvest fruits sample went from 1.6x104 to 8.6x105( cfu/g).The result of the pathogenicity test revealed that Saccharomyces cerevisiae, Geotricum candidium and Aspergillus glaucus, indicating that the organisms were responsible for the spoilage of the fruits.Fusarium spp and Aspergillus glaucus were the multicellular mould while S. cerevisiae, S. roiixii, S. fragilis, Debaroyomyces spp, Geotricum candidium, and Pichia species were the unicellular once.

TABLE OF CONTENTS

Tittle                                                                                                                i                      

Certification                                                                                                    ii

Dedication                                                                                                      iii        

Acknowledgements                                                                                        iv

Table of contents                                                                                            v

List of tables                                                                                                   vi

Abstract                                                                                                          vii

CHAPTER ONE

1.1    Introduction                                                                                             1

1.2    Aim and Objectives                                                                                 3

CHAPTER TWO

2.0    Literature Review                                                                                  4

2.1   Pineapple (Ananas comosus)                                                                  4

2.1.1   Four Different Varieties of Pineapples                                                4

2.1.1.1 Smooth Cayenne                                                                                 5

2.1.1.2   Abacaxi                                                                                             5

2.1.1.3 Queen                                                                                                  5

2.1.1.4 Red Spanish                                                                                        5

2.1.5 Uses and composition                                                                            6

2.12   Nutrition Information/Health Benefits of Pineapple                            8

2.1.3   Brief History of Pineapple                                                                   9

2.14   Microbial Spoilage of Pineapple.                                                        10

CHAPTER THREE

3.0    Materials and Methods                                                                        13

3.1    Materials                                                                                  13

3.2    Methods                                                                                               13

3.2.1   Samples collection                                                                               14                   

3.2.2   Preparation of Media                                                                           14                   

3.2.3   Fungal Counts                                                                                      14

3.2.4   Preparation of Samples                                                                        15

3.1.5   Isolation of Micro-Organisms                                                              15

3.1.6   Purification and Maintenance of pure Isolates                                    16

3.1.7   Identification of the isolates                                                                16

3.1.8   Fungal Characterization                                                                       16

3.1.9   Gram staining                                                                                       17

3.2      Pathogenicity of Isolated Fungi                                                          17

3.2.1   Pathogenicity Test                                                                               18

CHAPTER FOUR

4.1 Results                                                                                                      20

CHAPTER FIVE

5.0 Discussion, Conclusion and Recommendation                                         31

5.1 Discussion                                                                                                 31

5.2 Conclusion                                                                                                33

53. Recommendation                                                                                      33

REFERENCE

LIST OF TABLES

S/N                                                 Tiltle                                                                         Pages

1.      Fungi Species Found in the Unhealthy Pineapple Fruits                                              21             

2.      Mycological Identification Of Isolate Obtain From  Infected Pineapple                    23

3.      Mycological Identification Of Isolate Obtain From  Healthy Pineapple Inoculated With Pure Cultures Obtained From The Unhealthy Fruits                                       24

4.      Prevalence of fungal species in fruits                                                                           29                                            

CHAPTER ONE

1.1    INTRODUCTION

Food spoilage refers to various changes in which the food becomes less palatable or even toxic to consumers. These changes may be accompanied by alteration in taste, smell, appearance or texture.

Numerous microbial defects of agricultural crops are characterized by the types of microorganisms responsible for their deterioration (Akinmusire, 2011).A fruit is the edible part of matured ovary of a flowering plant. It is usually eaten raw. When matured, they may be either fleshly or dry. Freshly fruits are further classified into berry (orange, tomato, pineapple, pawpaw and banana), drupes (plume, coconut, cherry and almond) and pomes (apple and pear).

The dry fruits, unlike fleshy fruits which have unlayered pericarp are classified into dehiscent (pod, follicle and capsule) and indehiscent fruits like achene, samara, cashew etc. (Jolaosho,et al, 2010).

Fruits and vegetable are vital sources of nutrients to human being and animals. They give the body the necessary vitamins, fats, minerals, and oil in the right proportion for human growth and development. Fruits and vegetables however, have serious challenges to their existence. These include change in climatic condition, pest and microbial attack. Over the years , there has been an increase in the need to isolate, identify and compare the microorganisms associated with spoilage as a way of finding a means of controlling it (Akiroet al, 2015).

Susceptibility of fruits and vegetables is largely due to different chemical composition such as pH and moisture contents are associated with greater predisposition to microbial spoilage. The occurrence of fungi spoilage of fruits is also recognized as a source of potential health hazard to man and animals. This is due to their production of mycotoxins naturally occurring toxin chemical often of aromatic structure) which are capable of producing aflatoxin to man, following ingestion or inhalation.

These fruits are usually displayed on beaches and in baskets for prospective customers in the open market unit sold, thereby exposing them to further microbial infection besides those associated with these whole fruit surface and those from adjacent infected fruits (Baiyewe et al, 2007).In developing countries, postharvest deterioration are often more severe due to inadequate storage and transportation facilities. Microbial fruit infection may occur during the growth season due to climatic condition and the type of manure applied to it, harvesting, handling, transport, postharvest storage and marketing condition or after purchasing by the consumers. Fruits contain high levels of sugar and nutrient elements and their low pH value make them particularly desirable to fungal decay (Singh and Sharma, 2007). Studies by Licohen and Bruhn (2002) shows that fungi can survive and/or grow on flesh produce and that nutrient content (protein, carbohydrate and fat) of fresh produce support pathogens (Mbajiuka and Enya, 2014).

Fruits are affected by a wide range of microorganisms causing its decay. Spoilage microorganisms can be introduced to the crop on the seed itself during crop growth in the field during harvesting  and postharvest handling or during storage and distribution (loading and off-loading) (Barth et al, 2009).Those type of soil borne spoilage microbes that occur on produce are the same spoilage microorganisms that are present on harvesting equipment, on handling equipment, in the packaging house, in the storage facility, and on food contact surface throughout the distribution chain. Therefore, early intervention measures during crop development and harvesting through the use of good agricultural practice (GAP) will produce dramatic reduction in the yield loss due to deterioration at all subsequent steps in the food (Barth et al, 2009).

1.2    Aims and Objectives

The aim of this study is to isolate, characterize and identify the fungal pathogens of postharvest spoilage of pineapple fruit.

1.      To isolate the fungal pathogens associated with the spoilage of pre harvest of pineapple fruits.

2.      To isolate the fungal pathogens associated with the spoilage of post-harvest of pineapple fruits.

3.      To identify and characterize the isolated microorganisms.

4.      To determine the pathogenicity of the isolate microorganisms for pineapple fruits.

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