Production of fumonisin by strains of Fusarium moniliforme according to temperature, moisture and growth period

RESUMO

Production of fumonisins B1 (FB1) and B2 (FB2) by two Brasilian strains (LAMIC 2999/96 and 113F) and one American strain (NRRL 13616) of Fusarium moniliforme were evaluated in laboratory cultures subjected to different temperatures (20, 25, and 30ºC), and moisture contents (25, 34, and 42 per center) on corn substrate. The cultures were grown during 10, 20, 30, 45, and 60 days, totalizing 135 treatments with two repetitions for each one. The fumonisins were extracted with acetonitrile/water. The clean-up with end-capped C18 silica (C18ec) cartridges and fumonisin derivatization with o-phtaldialdeyde were carried out through an automated sample processor system (ASPEC), followed by quantification of the toxins through HPLC. Fumonisin production varied widely, reaching average yields from 0.25 to 5515.45 µg/g of FB1 and from 0.15 to 3032.10 µg/g of FB2. In the present work, the factors strain, temperature, moisture and days of fungal culture were evaluated, and all of them had a bearing on the amounts of fumonisins produced. The highest FB1 average yields were obtained by the strain 113F, under the following conditions 34 per center moisture content, 60 culture days, and temperature of 25ºC. The highest FB2 average yield was obtained by the same strain with cultures over 45 days, 42 per center moisture content, at the temperature of 25ºC. Via regression analysis, the ideal temperature for fumonisins production was, calculated as 24.5 and 24.3ºC (± 2ºC) for FB1 and FB2, respectively.