DETECTION OF ASPERGILLUS FLAVUS AND ASPERGILLUS PARASITICUS AND ESTIMATION OF AFLATOXINS IN SORGHUM PURCHASED IN UMUAHIA MAIN MARKET.

ABSTRACT

Sorghum is the fifth most important cereal after rice, wheat, maize and barley. Like every other plant, sorghum is attacked by microorganisms. Fungal species such as Aspergillus parasiticus and Aspergillus flavus grow on sorghum and consequently produce a mycotoxin known as aflatoxin. Aflatoxin is a toxic metabolite which causes acute illnesses such as liver damage ad cancer, even death when consumed in large quantity. Aspergillus parasiticus and Aspergillus flavus were isolated from sorghum seeds by culturing on Potato Dextrose Agar and the level of aflatoxin content of the seeds determined using ELISA method. Sorghum treated with only water, water and salt and water, salt and heat dried had a total viable count of 1.8x101cfu/ml, 7x101cfu/ml and 8x101cfu/ml respectively. The total aflatoxin content of the samples were 2.80ppb, 2.70ppb and 2.35ppb respectively. In addition, the aflatoxin content of the untreated sample was 4.00ppb. The germinative energy of all treated samples were 100%, 80% and 30% respectively.  Hence, producers should adopt treatment of raw sorghum with salt and heat-drying it in the HACCP steps to ensuring production of food safe for consumption. However, for production processes that require germination of the grains, the grains should first be germinated before heat-drying since it reduces the seeds germinative energy.

TABLE OF CONTENTS

Title Page i

Certification ii

Dedication iii

Acknowledgement iv

Table of Contents v

Abstract   x

Chapter one:  Introduction 1

1.1.   Overview 1

1.2.  Sorghum and Fungi 2

1.3.  Contamination conditions 3

1.4.  Aims and Objectives 4

Chapter two: Literature Review 5

2.1. Aflatoxins 5

2.2. Toxicology 10

2.3. Pathology 12

2.3.1. Aflatoxicosis 12

2.3.2. Aflatoxicosis and child health in Nigeria 12

2.3.3. Aflatoxicosis and hepatic deaseas 13

2.3.4. Other effects of aflatoxicosis 14

2.4. Diagnosis 15

2.5.  Prevention and control of exposure to aflatoxins 15

2.5.1. Education 15

2.5.2. Processing 16

2.5.3. Use of Antioxidants and Minerals 16

2.5.4. Aflatoxins Monitoring 16

Chapter Three: Materials and Methods 18

3.1. Isolation of Aspergillus flavus and Aspergillus parasiticus 18

3.1.1. Materials and instruments used 18

3.1.2. Sample preparation 19

3.1.3. Medium preparation 20

3.1.4. Plating the seeds 20

3.1.5. Total viable count on assay. 20

3.1.6. Counting of the colonies 21

3.1.7. Germinative energy 21

3.2. Estimation of aflatoxins 22

3.2.1. Materials and instruments used 22

3.2.2. Sample preparation 23

3.2.3. Aflatoxn detection 24

Chapter four:  Result 25

4.1. Total viable count (TVC) from the assay of all treated sample. 26

4.2. Germinative energy of treated samples. 27

4.3. Microorganisms isolated from all the samples 28

4.4. The Aflatoxin content of all samples 29

Chapter five: Discussion, Recommendations and Conclusion 30

5.1. Discussion 30

5.2. Recommendations 31

5.3. Conclusion 31

References

LIST OF TABLES

Table Title Page

2.1 Some Aflatoxins and Sources. 7

2.2 Chemical and physical properties of some

aflatoxins 8

 4.1  Total viable count (TVC) from the assay

 of all treated sample. 26

  4.2  Germinative energy of treated samples. 27

  4.3   Microorganisms isolated from all the samples 28

  4.4  The Aflatoxin content of all the samples 29

LIST OF FIGURES

Figure Title Page

 2.1.  Structure of aflatoxins B₁, B₂, G₁, and G₂ 9

 2.2. Pathways and consequences for Aflatoxin in

animal metabolism 11

CHAPTER ONE

INTRODUCTION

1.1 Overview

Sorghum (Sorghum bicolor (L.) Moench) is the fifth most important cereal after rice, wheat, maize and barley. It is the staple food grain for over 750 million on people who live in the semi-arid tropics of Africa, Asia and Latin America (Diener et al., 1981; Wilson et al., 1995; Marikunte et al., 2010). Global production of sorghum is currently estimated for 57.6 million tones, with Asian countries contributing 20% of the total production (Marikunte et al., 2010).

The sorghum crop is grown in dry conditions where other cereal crops yield much less. It is also grown with limited water resources and usually without the application of any fertilizers or other inputs. Studies showed that when corn required over 30 inches of water, sorghum required less than 23 inches (National sorghum producers, 2006; Gramene . org, 2015; Marikunte et al., 2010). Therefore, it is often referred to as “coarse grain” or “poor people’s crops” because it is a grain mainly consumed by the poor people (Halluka and Esele, 1992). The sorghum crop is still a primary source of energy, protein, vitamins and minerals for millions of poor people in areas where they are found (Bhat et al., 1997). It is used for human nutrition all over the world (Maunder, 2006). It is used for flours, porridges and side dishes, malted and distilled beverages, and specialty foods such as popped grain (Crop plant resources, 2006). Sorghum is also considered to be a significant crop for animal feeds and in the United States this is the major use grain (US grains Council, 2006, Gramene.org, 2015). It is also used for silage and pasturing of cattle and sheep (Carter et al., 1989). Other uses include: the use of sorghum fibers in wallboard, fences, biodegradeable packaging material and solvents. Dried stalks are used for cooking fuel, and dye can be extracted from the plant to color leather. A more recent use of sorghum is for ethanol. By – products form ethanol production, such as sorghum – DDGS (Distillers dried grain with soluble) are also finding a place in the market (Maunder, 2006; Crop plant resources, 2006; National Sorghum and producers, 2006; US Grains council 2006 and Sorghum – Wikipedia, 2015).

1.2. Sorghum and Fungi

The world’s food and feed crops are excellent substrate for toxigenic fungi and can be infected as developing seed, in the later phases of growth and in storage (Henry and Douglas, 2006). However, their ability to support prolific fungal growth and toxin production varies. Sorghum readily supports the toxigenic species of aspergillus section flavi; Asperigillus flavus and Aspergillus parasiticus (Gams et al., 1985; FAO, 2002). Aspergillus flavus produces aflatoxins B₁, and B₂ and the co-occurrence of aflatoxins B₁, B₂ G₁ and G₂ is attributed to Aspergillus parasiticus (Henry and Douglas, 2006).

The native habitat of these Aspergillus Species is in soil, decaying vegetation, hay and grains undergoing microbiological deterioration (Aflatoxin – Wikipedia, 2015). Aspergillus flavus is a saprotrophic and pathogenic fungus with a cosmopolitan distribution (Aspergillus flavus- Wikipedia, 2015). It is best known for its colonization of cereal grains, legumes and tree nuts. Post harvest rot typically develops during harvest, storage, and/or transit. Infections by this organism can occur while hosts are still in the field (Pre-harvest), but often show no symptoms (dormancy) until post harvest, storage and/or transport. In addition to causing pre-harvest and post-harvest infections, many strains produce significant quantities of toxic compounds known as mycotoxins (or Aflatoxins), which, when consumed, are toxic to mammals.  Aspergillus flavus is also an opportunistic human and animal pathogen, causing Aspergillosis in immune-compromised individuals (Amaike and Nancy 2011; Agrios, 2005).

Aspergillus parasticus is a mold that is also known to produce Aflaoxin. It is closely related to but separable to (based on DNA sequencing and amplified fragment length polymorphism finger printing) Aspergillus flavus. Aspergillus parasiticus produces aflatoxins B1, B₂ G₁ and G₂ unlike Aspergillus flavus which only produces B₁, and B₂ (Horn et al., 2009).

1.3. Contamination Conditions

Moisture and temperature are the most critical factors that influences contamination of sorghum by Aspergillus flavus and Aspergillus parasiticus on the farm or in storage and consequently the occurrence of mycotoxins. They may grow in the temperature ranges of 35 – 48⁰C and 4 – 20⁰C and moisture of 5-25% (Henry and Douglas, 2006). Other contamination conditions include damage from stressful conditions such as drought and availability of free oxygen for respiration. (Aflatoxin – Wikipedia, 2015).

1.4. Aims and Objectives

The aim of this research work is to isolate the aflatoxin producing fungi; Aspergillus flavus and Aspergillus parasiticus and to estimate the aflatoxin content of different sorghum samples treated in different conditions. These studies will be useful in the production of food (for local consumption and export) that will meet safety criteria and increase economic earnings.

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.