Two-dimensional profiles of fumonisin B 1 production by Fusarium moniliforme and Fusarium proliferatum in relation to environmental factors and potential for modelling toxin formation in maize grain

Abstract

This study has examined in detail the effect of temperature (7–37°C) and water availability (water activity, a w, 0.89–0.97) on fumonisin B 1 (FB 1) production by an isolate of Fusarium moniliforme and F. proliferatum on irradiated maize grain after incubation for 28 days. The optimum conditions for F. moniliforme and F. proliferatum were 30°C at 0.97 a w and 15°C at 0.97 a w, respectively. The maximum concentrations were 2861 mg kg −1 and 17,628 mg kg −1 dry wt. maize grain, respectively. At marginal a w/temperature conditions for growth (e.g. 0.89–0.91 a w) no FB 1 was detected (<0.1 mg kg −1). A high variability was found between replicates for F. moniliforme, but not for F. proliferatum. These data were used to construct two-dimensional diagrams of all the a w×temperature conditions favourable for FB 1 production for the first time. The data were also subjected to a polynomical regression, which demonstrated that there was a very good fit for the 15–30°C range of temperature and at 0.97 a w. However, at marginal environmental conditions this was not possible. This suggests that it may be possible to predict within a limited environmental range the potential for significant FB 1 production.