The effect of nonproducing Aflatoxisn Aspergillus flavus DA2 strain for Aflatoxin prevention of maize in the field and during storage

The strain Aspergillus flavus DA2 (AF) has been isolated from maize in Dong Anh district, Hanoi and has been determined that this is non producing aflatoxin strains and is highly competitive to A. flavus producing aflatoxin strains and other molds contaminated in maize. The AF formulation that is produced from A. flavus DA2 strain and having 100 CFU/g and carrier and applied to maize planting soil for three times in the experiment lot with area 28 x 360m2 with dose of 1kg/360m2. The results showed that: In the lot non applied by AF formulation, the total of A. flavus in the maize planting soil was 2.104 CFU/g in which the density of A. flavus producing aflatoxin was 1.8.104 CFU/g, equivalent 90% of total A. flavus isolates. In the lot applied by AF formulation for three times, the total of A. flavus in the maize planting soil was 2.2.104 CFU/g in which the density of A. flavus producing of aflatoxin was 1.103 CFU/g, equivalent 5% of total Aspergillus flavus isolated. The effect of AF formulation for maize ear in the preharvest stage was carried out to asses. The results showed that, in the lot lot non-applied by AF formulation 15% of kernels of the maize ear become mouldly, the average content of aflatoxin in maize ear samples was 5ppb (p 0.05), while in the maize ear samples applied by AF formulation for two and three times, almost maize kernels of maize ear have not yet mould, aflatoxin was not detected in the maize ear samples. After six months of storage, the results showed that, in the lot non-applied by AF formulation, maize kernel having dull color, 100% of maize kernal become moldly, the average content of aflatoxin in maize kernel was 98 ppb (p 0.05). IN the lot applied with AF formulation for three times and storage for six months, maize kernel having bright yellow colour, almost maize kernels have not yel moldy, the average content of aflatoxin in maize kernel was 3 ppb (p 0.05), the effect of aflatoxin reduction was 97%. This results revealed that the strain A. flavus DA2 is highly competitive to endemic A. flavus and having high effect to prevent aflatoxin contaminaton in maize in perharvest and postharvest stage.