PubMed · 6346949
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A K Foltz, J A Yeransian, K G Sloman. 1983. Food.. https://pubmed.ncbi.nlm.nih.gov/6346949/
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Fumonisins are a group of structurally related mycotoxins produced by Gibberella fujikuroi. The fungus produced fumonisin B1 (FB1) as early as 18 hour in a defined medium containing 1.25 mM or 2.5 mM ammonium phosphate, whereas fumonisin B1 production was repressed for 75 hour and 125 hour when mycelia were resuspended in media containing ammonium phosphate at 10 mM or 20 mM, respectively. Although total fumonisin B1 production was greater in resuspension cultures grown in higher concentrations of ammonium phosphate, the accumulation was independent of the inoculum size and carbon/nitrogen ratio. The addition of ammonium phosphate to cracked corn cultures also repressed fumonisin B1 production by 97%, and persisted for at least three weeks. Thus, biosynthesis of fumonisin B1 is regulated by a mechanism involving nitrogen metabolite repression, suggesting that control strategies that target the regulatory elements of nitrogen metabolism may be effective at reducing the risk of fumonisin contamination in food.
The separation of various carboxylic acids was performed on a polymethacrylate-based weakly acidic cation-exchange resin (TSKgel OApak-A) using ion-exclusion chromatography under the acidic elution conditions. When a diluted sulfuric acid solution was used as the eluent, highly sensitive conductimetric detection of carboxylic acids was achieved without increasing the background conductance of the eluent. This method was more sensitive than using benzoic acid eluent and enabled a good resolution of dicarboxylic as well as monocarboxylic acids. The addition of 5-20% methanol to the eluent considerably reduced the retention times of carboxylic acids with hydrophobic nature.