Abstract:
The samples of agricultural materials used for feeds were taken for the experiments, when the moisture content of materials were over 12% (v./w.), the contaminated fungi in the materials can grown and proliferated well. Fungal colonies were isolated, 98 strains, from agricultural materials. From primary screening test, 9 strains have been found to produce aflatoxin B1 and these strains were identified to genera. Six of them were Aspergillus W17, Aspergillus W54, Aspergillus W83, Penicillium W36, Rhizopus W26 and Fusarium W78, have been reported aflatoxin production strins whereas Fonsecaea W49, Aspergillus W79 and Curvularia W91 have not been reported to produce aflatoxin. Only ground peant, corn, coconut, scrap rice and soy bean were selected to be used in experiments. The ground peanut and corn were good materials that Aspergillus W83 could be grown and used it for aflatoxin B1 production, when compared to the other materials, especially to soy bean. Higher production of aflatoxin B1 by Aspergillus W83 on sterilized solid medium than on liquid one were detected. The effect of caffeine, sodium benzoate and the mixture of them were used in synthetic liquid medium the effects on spore germination, mycelial growth and aflatoxin production of Aspergillus W83 were examined. It was found that each of compound increased the log phase of mycelial growth and reduced the percentage of spore germination and the amount aflatoxin B1 production. The results showed the same of decreasing when the solid medium was used. Moreover, the mixture of caffeine and sodium benzoate were shown stronger effect than using either one of them.