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

This study has examined in detail the effect of temperature (7-37 degrees C ) and water availability (water activity, a(w), 0.89-0.97) on fumonisin B-1 (FB1) production by an isolate of Fusarium moniliforme and F. proliferatum on irradiated maize grain after :incubation for 28 days. The optimum condi tions for F. moniliforme and F. proliferatum were 30 degrees C at 0.97 a(w) and 15 degrees C at 0.97 a(w), respectively. The maximum concentrations we re 2861 mg kg(-1) and 17,628 mg kg(-1) dry wt. maize grain, respectively. A t marginal a(w)/temperature conditions for growth (e.g. 0.89-0.91 a(w)) no FB1 was detected ( < 0.1 mg kg(-1)). A high variability was found between r eplicates for F. moniliforme, but not for F. proliferatum. These data were used to construct two-dimensional diagrams of all the a(w) x temperature co nditions favourable for FB1 production for the first time. The data were al so subjected to a polynomical regression, which demonstrated that there was a very good fit for the 15-30 degrees C range of temperature and at 0.97 a (w). However, at marginal environmental conditions this was not possible. T his suggests that it may be possible to predict within a limited environmen tal range the potential for significant FB1 production. (C) 1999 Elsevier S cience B.V. All rights reserved.