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Influence of halogen salts on the production of the ochratoxins by aspergillus ochraceus wilh
(American Chemical Society, 2000-05) Stander, MA; Steyn, PS; Lubben, A; Miljkovic, A; Mantle, PG; Marais, GJ
The first report of the biological production of bromo ochratoxin B, by Aspergillus ochraceus Wilh. is presented as well as a study of the influence of potassium bromide, potassium iodide, potassium fluoride, and potassium chloride on the production of ochratoxin A and ochratoxin B. Potassium fluoride and potassium iodide inhibited the growth of the fungus, whereas potassium chloride substantially stimulated the production of ochratoxin A in shaken solid substrate fermentation on whole wheat or shredded wheat, generally giving a high yield of ochratoxins. Increasing levels of potassium bromide led to a decline in ochratoxin a production and an increase in bromo-ochratoxin B, ochratoxin B, and 4-hydroxy ochratoxin B. Nevertheless, A. ochraceus was much less versatile in the bromo analogues than other fungi, which produce metabolites containing chlorine. Analysis included aminopropyl solid-phase extraction column cleanup followed by quantitative analysis on reversed-phase HPLC using fluorescence detection and employing N-(5-chloro-2 -hydroxybenzoyl)-phenylalanine as an internal standard.