Colonisation and competitiveness of Aspergillus and Penicillium species on maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum

Abstract

The effects of different steady-state water activity levels (a(w), 0.93, 0.95 and 0.98) and temperature (15 and 25 degrees C) on colonisation patterns of Aspergillus and Penicillium spp., when colonising irradiated maize grain in the presence of Fusarium moniliforme and Fusarium proliferatum were assayed in terms of populations (colony forming units, CFUs g grain(-1)), seed infection and colonisation rates. The activity of F. moniliforme and F. proliferatum in grain reduced the presence of Aspergillus flavus, Aspergillus niger, Aspergillus ochraceus to some extent, particularly at 15 degrees C and higher water availabilities (0.95-0.98 a(w)). In contrast, colonisation patterns of Penicillium implicatum on maize grain were unaffected by either Fusarium spp. in terms of CFUs or seed infection. Correlations were made between CFUs, seed infection, growth rates and niche overlap indices and hyphal interactions to try and link key indicators of competitiveness and dominance by an individual species.