The relationship between mould biomass and the biosynthesis of aflatoxin B1 and G1 (AFB1 and AFG1) on solid substrates (whole and crushed maize grains) at temperatures from 15-40 °C and a water content in the substrate of 20-40% has been investigated. The experiments have been carried out with the aflatoxigenous mould Aspergillus parasiticus NRRL 2999 in pure culture and in mixed culture respectively, the latter with the common mould Fusarium graminearum ZMPBF 1244. The biomass growth during cultivation was measured by the chitin content, and the concentration of aflatoxins was determined by means of a fluorodensitometer. It has been established that the biosynthesis of the examined aflatoxins and their ratio primarily depend on the temperature of cultivation, rather than on the growth of the mycelium. The biomass of the mixed culture of A. parasiticus and F. graminearum after 42 days of cultivation reduces the amount of AFB1 by 20-35%, and the amount of AFG1 by 25-45%. The decrease of both toxin concentrations is more pronounced in the substrate with a higher initial water content and a higher temperature of cultivation. The biomass of the pure culture of A. parasiticus after 42 days of cultivation reduces the amount of AFB1 by 15-25% and the amount of AFG1 by 5-35% at the same parameters of mould growth and of water content in the substrate.
Kemija u industriji/Journal of Chemists and Chemical Engineers / Vol. 43, No. 11, pp.419-423