MOLECULAR CHARACTERIZATION OF AFLATOXIGENIC MOULDS AND EFFECTS OF PROCESSING ON AFLATOXIN CONTAMINATION OF SOME WHEAT MILLS FROM NORTHERN NIGERIA

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MOLECULAR CHARACTERIZATION OF AFLATOXIGENIC MOULDS AND EFFECTS OF PROCESSING ON AFLATOXIN CONTAMINATION OF SOME WHEAT MILLS FROM NORTHERN NIGERIA

 

 

CHAPTER ONE

1.0         INTRODUCTION

1.1 Background of the Study

Aflatoxins are mycotoxins produced by certain strains of moulds as secondary metabolites that represent a serious risk for human and animal health (Noelia et al., 2011; Dorwish et al., 2014). Aflatoxins are difuranocoumarin derivatives produced via a polyketide pathway (Yu et al., 2004; Juan et al., 2008) by two fundamental aflatoxigenic strains; Aspergillus flavus and Aspergillus parasiticus (Klich et al., 2000, Bennett and Klich, 2003; El-Khoury, 2011). Other very rare aflatoxin producers have also been reported (Horn, 2007). These two aflatoxigenic species have been reported to have different toxigenic profiles: Aspergillus flavus produce aflatoxin B1 (excreted in breast milk as M1), B2, cyclopiazonic acid, aflatrem, 3-nitropropionic acid, sterigmatocystin, versicolorin A and aspertoxin, Aspergillus parasiticus produces aflatoxin B1, B2, G1, G2 and versicolorin A (Wilson et al., 2002). Aflatoxin B1 is usually the most predominant and the most toxic metabolite within this family and is also the most potent genotoxic agent and hepatocarcinogen to man. The International Agency for Research on Cancer (IARC) classified aflatoxin B1 as a human group one carcinogen (IARC, 2002).

Incidence of aflatoxin poisoning has been known primarily to occur through ingestion of contaminated foods or feeds and to some extent through skin contact. The diseases caused by aflatoxin consumption are loosely called aflatoxicosis. There are two types of aflatoxicosis; acute aflatoxicosis which results in death, and while chronic aflatoxicosis give rise to cancer, immune suppression, and other ―slow‖ pathological conditions (Etzel, 2002). Aflatoxin contamination has been linked to increased mortality in farm animals and also significantly lowers the value of grains as an animal feed and as an export commodity (Aydin et al., 2008).

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MOLECULAR CHARACTERIZATION OF AFLATOXIGENIC MOULDS AND EFFECTS OF PROCESSING ON AFLATOXIN CONTAMINATION OF SOME WHEAT MILLS FROM NORTHERN NIGERIA