MICROORGANISMS ASSOCIATED WITH DETERIORATED TOMATOES

ABSTRACT

The study evaluated the occurrence of biodeteriogens in harvested tomato fruits and their antimicrobial sensitivity. A total of Twenty (20) Tomato fruit samples were purchased at guided random from five different markets (Ahieke, Orieugba, Ndioru, Umuariga and Gate 6 market) in Umuahia, Abia State. The Tomatoes were cultured on Sabouraud Dextrose Agar, Nutrient Agar (NA), and MacConkey Agar (MAC), using a pour plate technique. From the result obtained, a total of five (5) bacterial species, and three (3) fungal species and one (1) yeast species isolated. The biochemical, Morphological and cultural features revealed the bacterial and fungal isolates to be Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Serratia marcesens, Proteus mirabilis, Aspergillus niger, Fusarium oxysporum, Rhizopus stolonifer and Rhodotorula spp. Among the five major markets investigated however within Umuahia metropolis, Gate 6 market had the highest bacteria at 2.8x105. In the decayed tomato samples assessed, it was observed that Escherichia coli were the most frequently occurring isolates with a high percentage occurrence of 6(21.4%). The occurrence of Escherichia coli that is usually associated with faecal matter also affirmed poor hygiene in the markets. However, there were wide variations in the fungi population, with Aspergillus niger 4(14.3%) and Rhizopus stolonifer 4(14.3%) being most predominant and occurring isolates, followed by Rhodotorula sp., 2(7.1%) and Fusarium oxysporum 1(3.6%). It was also recorded in this study that Aspergillus niger and Rhizopus stolonifer dominated and had the highest percentage of occurrence over other fungal species.

TABLE OF CONTENTS

Title Page                                                                                                                                i

Certification                                                                                                                           ii

Dedication                                                                                                                              iii

Acknowledgements                                                                                                                iv

Table of Contents                                                                                                                   v

List of Tables                                                                                                                          vii

Abstract                                                                                                                                  viii

CHAPTER ONE

1.0       Introduction                                                                                                                1

1.1       Aim and Objectives                                                                                                    4

CHAPTER TWO

2.0       Literature Review                                                                                                       5

2.1       Brief Description of Tomato Fruit                                                                              5

2.2       Antibiotic Sensitivity of Bacterial and Fungal Isolates from Tomato

            (Solanum Lycopersicum) Fruit                                                                                   6

2.3       Control of E. coli and Spoilage Microorganisms in Tomato Sauce and Paste

            Using a Synergistic Antimicrobial Formula                                                               8

2.4       Isolation and Identification of Fungi Associated With Postharvest

            Decay of Lycopersicum Esculentum Sold in Abakaliki, Nigeria                                    10

2.5       Isolation of Microorganisms Associated With Deterioration of Tomato

            (Lycopersicon Esculentum) and Pawpaw (Carica Papaya) Fruits                                    11

CHAPTER THREE

3.0       Materials and Methods                                                                                               14

3.2       Source/Sample Collection                                                                                          14

3.3       Materials and Media Used                                                                                          14

3.3.1    Sterilization of Materials                                                                                            14

3.4       Processing of Samples                                                                                                14

3.5       Microbiological Studies                                                                                             15

3.5.1    Inoculation and Enumeration of Microorganisms                                                      15

3.6       Microbial Characterization and Identification                                                           15

3.6.1    Identification of Bacterial Isolates                                                                             15

3.6.1.1 Gram Staining                                                                                                             15

3.6.2    Biochemical Tests                                                                                                      16

3.6.2.1 Indole Test                                                                                                                  16

3.6.2.2 Carbohydrate Utilization Analysis                                                                             16

3.6.2.3 Catalase Test                                                                                                               16

3.6.2.4 Oxidase Test                                                                                                               16

3.6.2.5 Coagulase Test                                                                                                           17

3.6.2.6 Citrate Utilization Test                                                                                               17

3.6.2.7 Motility Test                                                                                                               17

3.6.2.8 Methyl Red Test                                                                                                         17

3.7       Spore Staining                                                                                                            17

3.8       Subculturing/Purification and Identification of Test Fungi Species                                    17

3.9       Identification of Fungal Isolates                                                                                 18

3.9.1    Wet Preparation                                                                                                          18

3.9.2    Colonial Morphology                                                                                                 18

3.10     Antimicrobial Susceptibility Testing                                                                         18

CHAPTER FOUR

4.0       Results                                                                                                                        20

CHAPTER FIVE

5.0       Discussion and Conclusion                                                                                        27

5.1       Discussion                                                                                                                   27

5.2       Conclusion                                                                                                                  30

              References

LIST OF TABLES

CHAPTER ONE

1.0       INTRODUCTION

Tomato (Solanum lycopersicum L.) is a berry, annual, short‒lived herbaceous plant of the Solanaceae family. It is usually sprawls on the ground, and could reach about 1‒5 m height (Wogu and Ofuase 2014). It has a weak woody stem covered with glistering yellow to reddish glandular hairs, rarely vine over other plants. The leaves are between 10 and 25 cm long with 5–9 leaflets on the petioles, which are odd and pinnate. Each leaflet is about 8cm long with serrated margins. Flowers are yellow from 1–2 cm with fine and pointed lobes on its corolla (Ijato et al. 2011). The fruit is edible with a smooth epicarp, and varies in shape and size. Immature fruit is green and becomes yellow or bright red as it ripens (Chinedu and Enya, 2014). Tomato plant is cultivated in the savannah agro-ecological zone of Nigeria during cropping season and dry season under furrow irrigation. The plant usually produces higher yield and better fruit qualities with minimal foliar diseases under irrigation compared to those cultivated during the cropping season.

Tomato (Solanum lycopersicum) is one of the highly nutritious food ingredient used in the preparation of food all over the world (Ogunbanwo et al., 2014). Its utilization as an ingredient in vegetable salads, other dishes and its processing into different products like puree, ketchups and juice is well documented. Nutritionally, it contains a large amount of water, niacin, calcium and vitamins especially A, C, E which are important in the metabolic activities of man and protects the body against diseases (Taylor, 2007). Lycopene (acarotene) an essential component of tomato contributes in the prevention of cardiovascular disease and cancer of the prostrate (Bernard et al., 1999).

Tomato fruit ranks 7th as the most important staple crop worldwide, after wheat, maize, rice, soybeans, cassava and potatoes, with production estimate of approximately 160 million tonnes, cultivated on 4.8 million hectares in the year 2011 (Ogunbanwo et al., 2014). The fruit is consumed as vegetable, dietary supplement, eaten raw as salad and for garnishing assorted cooked food or condiment, contributing to a healthy well‒balanced diet. It is also valuable in the food industries (Fatima et al., 2015; Bello et al. 2016). Ripened raw tomato fruit of 100g constituents are carbohydrate 4 g, energy 75 kg (18 k), dietary fiber 1g, sugar 2.6g, fat 0.2g, vitamin C (22%, 13 mg), protein 1g, and water 95 g (Ijato et al., 2011). Nutritionally, the fruit contains calcium, niacin, flavonoids, lycopene, beta-carotene, derivatives of hydroxycinnamic acid, high amount of water and vitamins, specifically A, C, and E which are very vital in metabolic activities of humans (Gerszberg et al., 2015).

The deep red coloration of the fruit has been attributed to lycopene, a form of carotenoid pigment with a powerful antioxidant that protects humans against diabetes, cardiovascular diseases and anti-cancer as well as preventing blood clotting (Abdul‒Hammed et al. 2015). High pH (4.9‒6.5), water and nutrient contents enhance microbial growth such as bacteria and fungi, which degrade the nutrients through enzymes production (Ogunbanwo et al. 2014), and heighten spoilage susceptibility, thereby reducing the nutritional and market values. Contamination of tomato fruit by microbes is due to poor handling during the production chain, transportation, distribution, marketing and storage (Akinyele and Akinkunmi 2012). Environmental factors such as temperature, frost and rainfall constituted adverse effects on quality of the fruit and their storage shelf life (Akinyele and Akinkunmi 2012). Besides the damage to the fruit, microbial infections poise potential health hazards to animals and humans, as some of the organisms are pathogenic, producing toxins capable of causing diseases such as diarrhoea, gastroenteritis, respiratory infections and meningitis, if ingested (Barth et al., 2009). The Centre for Disease Control and Prevention estimated 76 million cases of food borne diseases yearly, and the etiology is predominantly of microbial origin (Wokoma, 2008). Ghosh, (2009) reported that fungi were more virulent than bacteria in tomato fruit spoilage. The main tomato diseases in the forest and savanna ecologies of Nigeria are Aspergillus niger, Pseudomonas solanacearum, Sclerotium rolfsii and Fusarium oxysporum (Ogunbanwo et al., 2014). The need for an elaborate study of contaminating pathogens of the tomato fruit becomes essential, considering tomato fruit as a ready‒to‒eat food with minimal processing or eaten raw and can possess serious threats to food safety (Ofor et al., 2009). Similarly, the high price of fresh ripened tomato fruit sold in the Nigerian markets is a major concern. A relatively cheaper spoiled fruit consumed by the poor contain microbial infectious diseases.

The characteristic flavor of tomato is produced by the complex interaction of the volatiles and non-volatile components (Buttery, 1993). The nutritional value of tomato products is a topic attracting much attention, particularly regarding the effects resulting from food processing and storage treatments. Among the common post-harvest fungal pathogens of tomatoes are Pencillium expansum, Monilinia laxa and Rhizopus stolinifer (Pla et al., 2005). Many Lactic Acid Bacteria strains are able to produce protein compounds with efficient antimicrobial effect, which are known as bacteriocins (Davidson and Harrison, 2002). In recent times, the understanding of the preservation mechanisms of Lactic Acid Bacteria is being exploited for industrial production of foods (Trias et al., 2008) because of their natural acceptance as Generally Recognized as Safe (GRAS) for human consumption and exhibit antimicrobial property. There is a complimentary effect by the production of acid and antimicrobial compounds that increases inhibition of both pathogen and spoilage bacteria (Artés et al., 1999).

Susceptibility of fruits and vegetables is largely due to differential chemical composition such as pH and moisture contents are associated with greater predisposition to microbial spoilage. The occurrence of fungal spoilage of fruits is also recognized as a source of potential health hazard to man and animal. This is due to their production of mycotoxins (naturally occurring toxic chemical often of aromatic structure) which are capable of producing aflatoxin in man, following ingestion or inhalation. These fruits are usually displayed on benches and in baskets for prospective customers in the open markets until sold, thereby exposing them to further microbial infection beside those associated with these whole fruit surface and those from adjacent infected fruits (Baiyewu et al, 2007). In developing countries, post harvest deterioration are often more severe due to inadequate storage and transportation facilities. Microbial fruits infection may occur during the growth season, harvesting, handling, transport and post harvest storage and marketing conditions, or after purchasing by the consumer.

1.1       AIM AND OBJECTIVES

To determine the occurrence of spoilage microorganisms in tomato fruit and their antimicrobial sensitivity, while the specific objectives are;  

·       To isolate, identify and characterize micro organisms present in tomato fruit sample

·       To determine the percentage of occurrence of various isolate from tomato fruit sample

·       To determine the sensitivity profile of various isolate present in tomato fruit sample

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.