Factors affecting the growth of Fusarium proliferatum and the production of fumonisin B1: oxygen and pH.

Fumonisins are mycotoxins produced primarily by Fusarium moniliforme and Fusarium proliferatum in corn. In liquid culture, production of fumonisin B1 (FB1), the most common moiety of the family of fumonisins, can be obtained using a defined medium that is nitrogen-limited. Under nitrogen-limited conditions both growth and the production of FB1 were greatly influenced by pH and aeration. At pH above 5.0, F. proliferatum grew normally but produced little FB1 (< 100 micrograms m-1). At pH below 5.0, there was less growth but substantially more FB1. Below a pH of 2.5, both growth and metabolism were slower with very little FB1 produced. When the optimal pH range of between 3.0 and 4.0 under well-aerated conditions was used, both growth and FB1 production were high. However, under oxygen-limited conditions, less growth occurred, glucose consumption was increased, and no FB1 was produced.