BACTERIA ASSOCIATED WITH THE CONTAMINATION AND SPOILAGE OF AFRICAN PEAR (DACRYODES EDULIS) SOLD IN DIFFERENT PARTS OF UMUAHIA METROPOLIS, ABIA STATE

ABSTRACT

African pear (Dacryodes edulis) stores badly and in many cases is consumed raw without washing. The study was carried out to evaluate the presence of pathogenic bacterial contaminant and pulpy mesocarp of fresh and deteriorated Dacryodes edulis fruit sold in different locations of Umuahia metropolis. Twenty samples comprising fresh and deteriorated (Dacryodes edulis) fruits were analyzed for bacterial contamination. One gram of the pulpy mesocarp of each sample was sliced into tiny pieces and soaked into 5ml of physiological saline from where 10 fold serial dilutions where made. This was streaked in Blood, Nutrient, MacConkey and Manitol Salt Agar and incubated aerobically at 370 for 24hrs. Bacterial isolates were identified by standard bacteriological methods. Bacterial isolates in the study includes Escherichia coli 16 (25%), Klebsiella spp, 11 (17.19%), Proteus spp 8 (12.5%), Coans 6 (9.38%), S.aureus 7 (10.94%), Pseudomonas aeruginosa 4 (6.25%), Streptococcus spp 7 (10.94%), Bacillus spp 5 (7.81%). Comparative analyses of bacterial diversity in fresh and deteriorated sample revealed a pattern of complete absence of staphylococci organism in the deteriorated samples. Mean microbial loads ranged from 1.5×103 -6.0×103 and 2.0×105 _   1.5×105 in the fresh and deteriorated samples respectively. Antibiotics susceptibility pattern was done by disc diffusion technique. The isolates where susceptible to most of the antibiotics used.

Table of Contents

 TITLE PAGE

CERTIFICATION                                                                                                      ii

DEDICATION                                                                                                           iii

ACKNOWLEDGEMENT                                                                                          iv

TABLE OF CONTENTS                                                                                           v

LIST OF TABLES                                                                                                      ix

ABSTRACT                                                                                                               x

CHAPTER ONE

1.0   INTRODUCTION                                                                                                1

1.1   Background Of Study                                                                               2

1.2   Aim of study                                                                                              2

1.3   Objectives of the study                                                                              2

1.4   Limitations                                                                                                 3

CHAPTER THREE

2.0   LITERATURE REVIEW                                                                                     4

2.1   Botanic description                                                                                    4

2.2   Habitat                                                                                                       5

2.3   Biology                                                                                                      5

2.4   Ecology and biophysical limits                                                                 5

2.5    Products                                                                                                   6

2.5.1         Food                                                                                                 6

2.5.2         Fodder                                                                                              6

2.5.3      Apiculture                                                                                          7

2.5.4      Timber                                                                                                7

2.5.5      Gum or resin                                                                                       7

2.5.6      Earthenware                                                                                        7

2.5.7      Tanning or dyestuff                                                                            7

            2.5.8      Lipids                                                                                                  8

2.5.9      Essential oil                                                                                         8

            2.5.10    Medicine                                                                                              8

       2.6        SERVICES                                                                                          9

2.6.1        Shade of shelter                                                                                   9

2.6.2        Ornamental                                                                                          9

2.6.3        Soil improver                                                                                       9

2.6.4        Intercropping                                                                                       9

2.6.5       Tree management                                                                                 10

            2.7        Germplasm management                                                                      10

2.8         Pests and diseases                                                                                 10

            2.8.1     Diseases                                                                                                10

            2.8.2     Pest                                                                                                       10

2.9         Health benefits of African pear consumption: a review                       11

2.10   Bacterial associated with surface contamination and spoilage of African pear                      (dacryodes edulis)                                                                                             12

2.10.1     Escheriachia coli.                                                                                12

2.10.2     Klebsiella specie                                                                                  13

2.10.3     Staphylococcus aureus                                                                        14

2.10.4     Other Staphylococcus specie                                                               15

2.10.5      Bacillus subtilis                                                                                  15

2.10.6      Pseudomonas aeruginosa                                                                  16

2.10.7     Proteus specie                                                                                     16

CHAPTER THREE

          3.0 Materials and Methods                                                                                18

3.1   Study area                                                                                                   18

3.2 Materials and Reagents                                                                                18

3.3 Sample collections                                                                                       18

3.4 Sample preparation, Innoculation and Isolation                                          19

          3.5 Media preparation                                                                                        19

          3.6 Sterility                                                                                                        19

          3.7 Isolation and Identification of Bacterial isolate                                          20

          3.8 Determination of Bacterial load                                                                  20

          3.9 Characterization of Bacterial isolates                                                          20

          3.9.1 Gram staining                                                                                            20

          3.9.2 Catalase test                                                                                               21

          3.9.3 Coagulase test                                                                                          21

          3.9.4 Citrate test                                                                                               21

          3.9.5 Motility, Indole, Urease test (MIU)                                                        22

          3.9.6 Triple sugar iron test                                                                               22

           3.9.7 Oxidase test                                                                                            23

          3.10 Antibiotic sensitivity test                                                                          23

           3.11 Data analysis                                                                                            23

CHAPTER FOUR

4.0  Result                                                                                                          24

CHAPTER FIVE

          5.0 Discussion                                                                                                   32        

          5.1 Conclusion and Recommendation                                                              33  

REFERENCES                                                                                                         34

                     LIST OF TABLES

Tables                                                             Titles                                                                 Pages

1                                 Number of fruit sample from different selling outlets                                     25

2                                 Morphological identification of isolates                                                   26

3                                 Biochemical characterization of the isolates                                             27

4                                 Comparative analysis of bacterial diversity of fresh and deteriorated fruits  28

5                                 Relative abundance of isolates                                                                  29

6                                 Mean bacterial load of isolates                                                                  30

7                                 Antibiotic susceptibility profile of the bacterial isolates                                     31

CHAPTER ONE

1.0 INTRODUCTION

African pear (Dacryodes edulis) which belongs to the family of Burseraceae, is known as Safou in French, ube in Igbo, elemi (Yoruba), eben (Efik) and orumu (Benin) (Kengue et al., 2002; Nwokeji et al., 2005). They are found in Cabinda, Cameroon, Congo (Brazzaville), Congo, Kinshasa, Gabon, Ghana, Equitorial, Guinea, Nigeria and Sao Tome (Onana, 2008). In south-east Nigeria, the trees are grown around homesteads and flowering takes place from January to April. The major fruiting season is between May and October. In both rural and urban areas of Cameroon, the fruits are boiled or roasted and then eaten with cassava or maize .Dacryodes edulisis a dioecious shade loving species of non-flooded forests in the humid tropical zone (Leakey, 1999; Leakey et al., 2002; Waruhiu et al., 2004; Anegbeh et al., 2005) where its seed is widely cultivated for the production of its fruits which has vast economic and health-related benefits (Verheij, 2002). It consists of a seed surrounded by a pulpy butyraceous pericarp, which is the edible portion consumed either raw or cooked. Its fruit and seed is rich in oils, proteins, minerals and vitamins which makes it an excellent source of nutrition to  consumers, stimulating its increased production and commercialization for decades (Sofowora, 1982). Its oil has been found suitable for cosmetics and food, while the flower nectar provides a good honey (Ayuk et al., 1999; Verheij, 2002).

The principal value of African pear fruits lies in their pulpy mesocarp of thickness 3 to 9 mm², rich in fatty acids and amino acids. The fruit is a major and cheap source of nutrients containing protein (6.39%), oil (33.5%), fibre (10.6%), ash (3.33%) and carbohydrate (47.7%) and a high energy value of 545kcal per 100g. it makes significant dietary contribution, which ameliorates the food problems in developing countries, since it is available at most seasons including strategic periods of the year when conventional staples that are difficult to store are scarce (Nwanekezi and Onyeagba, 2007). The oils from the pulps and seeds can be used in foods, pharmaceuticals and cosmetics manufacturing as well as numerous uses (Okorie et al., 2000). They are rich in unsaturated fatty acids and are comparable to other currently used vegetable oils (Osagie and Odutuga, 1986). In addition to the above, the tree and leaves are used as medicine; livestock feed and ornamental wood (Nwanekezi and Onyeagba, 2007).

The poor shelf life of the fruit has led to its high perish ability, huge losses and market glut as microorganisms easily attack the fruit at will.

1.1 BACKGROUND OF STUDY

Fruits of Dacryodes edulis stores badly as it easily gets spoilt and in many cases consumed raw without washing. Its high nutritional contents pre-supposes that an array of microorganisms especially bacteria may be involved in its contamination and spoilage. This study was aimed at isolating and identifying the possible bacterial organisms responsible.

1.2 AIM OF STUDY

To evaluate the presence or absence of pathogenic bacteria contaminants on the pulpy mesocarp of fresh and deteriorated Dacryodes edulis sold in different locations in Umuahia metropolis.

1.3 OBJECTIVES OF THE STUDY

The specific objectives of the study area

1.     To isolate and identify pathogenic bacteria organisms found on the pulpy mesocarp of both fresh and deteriorated Dacryodes edulis.

2.     To compare the bacterial diversity and relative frequency of occurrence of bacterial isolates from fresh and deteriorated Dacryodes edulis fruits

3.     To estimate bacteria load.

4.     To determine the antibiotic sensitivity pattern of bacteria isolated from the study.

1.4 LIMITATIONS

This study was hugely incapacitated by its inability to procure antisera for the identification of toxigenic strains of E. coli and other cutting edge materials needed for in-strain differentiation of organisms of the same species.

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