Influence of halogen salts on the production of the ochratoxins by Aspergillus ochraceus Wilh.

The first report of the biological production of bromo ochratoxin B by Aspe rgillus ochraceus Wilh. is presented as well as a study of the influence of potassium bromide, potassium iodide, potassium fluoride, and potassium chl oride on the production of ochratoxin A and ochratoxin B. Potassium fluorid e and potassium iodide inhibited the growth of the fungus, whereas potassiu m chloride substantially stimulated the production of ochratoxin A in shake n 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-ochrat oxin B, ochratoxin B, and 4-hydroxy ochratoxin B. Nevertheless, A. ochraceu s was much less versatile in the bromo analogues than other fungi, which pr oduce metabolites containing chlorine. Analysis included aminopropyl solid- phase extraction column cleanup followed by quantitative analysis on revers ed-phase HPLC using fluorescence detection and employing N-(5-chloro-2 -hyd roxybenzoyl)-phenylalanine as an internal standard.