Production of aflatoxins by Aspergillus flavus and Aspergillus niger strains isolated from seeds of pulses

Author: Amira Hassan Abdullah Al-Abdalall

Received 7 January 2009, accepted 12 April 2009.

Abstract

Fourteen Aspergillus flavus and three A. niger strains were isolated from seeds of lupine (Lupinus albus L.), mung bean (Vigna radiata L.), faba bean and field bean (Vicia faba L.) and lentil (Lens culinaris). The aflatoxin production of isolates was tested by two different bioassay methods as measuring the inhibitory effect on okra seed germination and bacterial growth. Toxic effect has different degrees including delay of seed germination, yellowish plant and inhibition of Bacillus subtilis growth. Autoclaving of fungal filtrate, freezing or microwaves has no effect on bacterial growth inhibition. B1 and B2 aflatoxins were found in all fungal filtrates with concentrations ranging from 38 to 496 µg/litre (the permitted limit is 20 µg/litre), and G1 and G2 aflatoxins were also produced by some isolates. Results proved the stability of such toxins.

Key words: Aflatoxins B1, B2, G1, G2, fungi, mycotoxins, toxic effects, bioassay methods, bean, lupine, lentil seeds.