Culture characteristics and aflatoxin producing strains of Aspergillus flavus from maize grains

Accepted: 21-03-2015 The known mycotoxin the most important which have been studied mostly because of possible hazards to human health are the afltoxins.Aflatoxins produced very commonly by two species of Aspergillus viz. Aspergillus flavus and Aspergillus parasitic. In this study growth pattern and culture characteristics of Aspergillus flavus isolates were studied. Twelve strains of A. flavus were isolated from three varieties of maize seed. To study the growth pattern of different isolates of A.flavus, CZA and GNA media were used. The different strains of A.flavus showed great variation in diameter of colony and growth pattern. There was also variation in the colour of colony from both sides. Aspergillus flavus is the most important aflatoxin producing mould. This species in maize produces carcinogenic, mutagenic and teratogenic secondary metabolites. Estimation of aflatoxin is generally monitored by ELISA & HPTLC.. Twelve isolates of Aspergillus flavus isolated from three maize varieties were tested by cultural method for aflatoxin detection, which is inexpensive and rapid. Two isolates viz. AF1 and AF12 were found highly toxic which showed dark pink colour development ,while AF2 were found moderately toxigenic ,because these isolates turned into moderate pink color, while eight isolates viz. AF3, AF4, AF5, AF7, AF8, AF9, AF10, AF11 exhibited light pink colour after treatment with ammonium vapor ,were low toxigenic. Among all the isolates tested only one viz. AF6 isolate were found to be nontoxigenic. The results of ammonia vapors test were up to 90% with the result of toxin detection by high pressure thin layer chromatography (HPTLC).