Identification and control of specific aflatoxin-producing fungi in stored maize seeds in awka using azadirachta indica (neem) and garcinia kola seeds

Abstract

Four fungal isolates were identified in this study of which three were Aspergillus species with Aspergillus flavus having the highest frequency followed by A. parasiticus. The result of high frequency of Aspergillus flavus and Aspergillus parasiticus in the Zea mays sample revealed production of aflatoxins. Maize sample in Awka was found to contain aflatoxin B1 (9.60ppb) and B2 (13.3ppb). Inhibition of A. flavus and A. parasiticus with Azadirachta indica and Garcinia kola seed extracts showed that the test plant extracts were effective for reducing mycelial growth on the test organism. Methanolic extract of G. kola showed antifungal inhibitory activity on the test organisms and the highest at 10% concentration. With ethanol extracts of G. kola, the antifungal activity was effective i.e. for inhibition of A. flavus and A. parasiticus, with A. parasiticus having the higher percentage inhibition at 10%. Inhibiting growth of Aspergillus flavus and Aspergillus parasiticus using methanolic and ethanolic extracts of neem seeds was effective in the inhibition of the test organism at 10%. The methanolic and ethanolic extracts of combined Garcinia kola and neem seeds revealed effective inhibition of A. flavus and A. parasiticus with ethanolic extracts of the combined test plants exerting the highest inhibition against A. flavus (80.43±3.62). The extracts from this plant show the ability to suppress growth of toxigenic A. flavus and A. parasiticus. Phytochemical analysis showed that the methanolic and ethanolic extracts of G. kola and neem seeds showed the presence of secondary metabolites and this may be a reason for the inhibitory activity on A. flavus and A. parasiticus. Results from this study will be important in planning a management strategy against aflatoxin-producing fungi and other fungi associated with spoilage of stored food products.