Abstract 89

Blaha,-J; Lohnisky,-J

Institute of Tropical and Subtropical Agriculture, Agricultural University, Prague, 160 21 Praha 6-Suchdol, Czechoslovakia.

Tropical-Science. 1990, 30: 1, 33-40; 8 ref.

Two experiments were conducted for the determination of aflatoxin production by strains of A. flavus isolated from Vietnamese yellow maize and groundnut oil cakes. These strains were inoculated into sterilized (irradiated) maize, wheat and feed mixture (Exp 1). The A. flavus strain, isolated from groundnut oil cakes, was inoculated into unirradiated maize and feed mixture (Exp 2). The moistened and dry samples of inoculated feeds were stored for 50 d at 20 ø C and 30 ø C. The feed samples were analysed for aflatoxin B1 (AFB1) before the experiments and then after 10, 20, 30, 40 and 50 d. The feed samples were microbiologically examined before the experiments and then after 30 and 50 d. A. flavus grew more intensively in the moistened samples (approx. 20% moisture) and produced much more of AFB1 than in unmoistened samples. The strain of A. flavus isolated from groundnut oil cakes produced more AFB1. Most feed samples attained peak production of AFB1 between 20 and 40 d of storage depending on moisture and temperature (max. production 520.6 mg/kg). The growth and production ability of A. flavus was lower in the mixture of fungi obtained from unirradiated feeds.