Isolation of Filamentous Fungi Species Contaminating Some Nigerian Food Commodities

Mary Augustina Egbuta,Patrick Berka Njobeh,Judith Zanele Phoku,Mulunda Mwanza,Cynthia Adaku Chilaka,Micheal Francis Dutton

doi:10.5539/jfr.v4n1p38

Abstract

Samples of maize, rice, cocoa and cocoa-based powder beverage) collected from different stores and markets in south-western Nigeria were screened for filamentous fungi contamination using conventional and molecular methods. Samples were cultured aseptically on potato dextrose agar (PDA), ohio agricultural experimental agar (OEASA), Malt Extract Agar (MEA) and Czapek Yeast Agar (CYA) prior to fungi isolation. Conventional methods comprising of macroscopic and microscopic evaluation of isolated fungi species were implemented in the analysis for identification of fungi species. Molecular method of identification involved DNA extraction, Polymerase chain Reaction (PCR) using ITS-1/ITS-4 primer pair and nucleotide sequencing. Results obtained indicated a range of filamentous fungi genus including Aspergillus, Penicillium, Fusarium, Alternaria, Cladosporium and Rhizopus contaminating the food commodities with Aspergillus and Penicillium species dominating most of the samples. High incidences were recorded for Aspergillus flavus, Aspergillus niger and Aspergillus fumigatus in most of the samples screened. The occurrence of these filamentous fungal species pose a reason for concern as most of these fungal species are known producers of toxic substances. This study was carried out to contribute to mycological screening of different Nigerian food commodities for a variety of filamentous fungi species.

Highlights

Filamentous fungi Aspergillus, Penicillium, Fusarium, Alternaria, Acremonium, Cladosporium and Curvularia are common micro-organisms in the environment found in the soil, air and contaminated food (Gołofit-Szymczak & Górny, 2010; Pitt & Hocking, 1997) due to their ubiquitous nature and because fungi can grow on any substrate under favourable conditions (Klein & Paschke, 2004)
Results obtained indicated a range of filamentous fungi genus including Aspergillus, Penicillium, Fusarium, Alternaria, Cladosporium and Rhizopus contaminating the food commodities with Aspergillus and Penicillium species dominating most of the samples
Cocoa and cocoa- based powder beverages were contaminated mainly with a range of Aspergillus species dominated by the prevalence of Aspergillus flavus (82.4%), Aspergillus fumigatus (76.5%), Aspergillus niger (82.4%), Aspergillus parasiticus (54.6%) and Aspergillus ochraceus (52.9%) with lesser incidences of Penicillium and Fusarium species

Summary

Introduction

Filamentous fungi Aspergillus, Penicillium, Fusarium, Alternaria, Acremonium, Cladosporium and Curvularia are common micro-organisms in the environment found in the soil, air and contaminated food (Gołofit-Szymczak & Górny, 2010; Pitt & Hocking, 1997) due to their ubiquitous nature and because fungi can grow on any substrate under favourable conditions (Klein & Paschke, 2004). Nigeria being the most populous nation in Africa with a population of over 130 million people has its domestic economy dominated by agriculture, which accounts for about 40% of the Gross Domestic Product (GDP) and two-thirds of the labour force. Agriculture supplies food, raw materials and generates household income for the majority of the people especially in the rural areas. Farming is often of the subsistence variety, characterized by simple tools and shifting cultivation as well as improper methods of storage and transportation of agricultural products. Large scale agriculture is not so common with few large scale farmers in the country. These small farms produce about 80% of the total food consumed (Akande, 2010)

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Conclusion