Comparisons of water activity and temperature impacts on growth of Fusarium langsethiae strains from northern Europe on oat-based media

This study has examined the effect of water activity (a(w), 0.995-0.90) and temperature (10-37 degrees C) on the lag phases prior to growth, growth rates and used models to develop two dimensional profiles for optimum and marginal conditions for two strains of Fusarium langsethiae from four northern European countries (UK, Norway, Sweden, and Finland) on an oat-based medium. Results showed that the optimum a(w) for growth was at 0.98-0.995 and 25 degrees C. The limit for growth of the strains was at 0.92-0.93 a(w) with minima of 10 degrees C. No growth occurred at 37 degrees C. The lag phases prior to growth were lowest under optimum conditions and extended to10days at marginal conditions. Statistical analyses of intra and inter-strain differences in terms of both lag phases prior to growth and growth rates were not statistically significant. However, a(w) and temperature were statistically significant factors. Two dimensional profiles for strains from each country of origin were built to identify optimum and marginal conditions for F. langsethiae for the first time. These environmental profiles will be beneficial for improving the ecological knowledge of this species which is able to produce trichothecene mycotoxins in a range of temperate cereals.