Production of Ochratoxin A by Aspergillus Ochraceus

The effects of growth conditions, trace metals, carbon and nitrogen source on ochratoxin A (OTA) production by Aspergillus ochraceus NRRL 3174 were investigated in submerged liquid culture medium. No correlation between biomass production and OTA synthesis was observed. OTA production depended on the initial pH and was influenced by changing the pH of the culture medium. This effect was not due to differences in the availability of metal ions. At pH 6.5, 0.2 mg l^?1 Zn increased biomass and OTA production by 50%. Fe at 0.12 mg l^?1 resulted in a 40% decrease in the amount of OTA/biomass although the quantity of biomass was not affected. Amounts of OTA produced per biomass increased with decreasing glucose concentrations. Lactose triggered the highest amounts of OTA/biomass despite low yields of biomass. NO₃ ^? stimulated the amount of OTA/biomass by 25% and NH₄ ⁺ reduced the amount of OTA/biomass by 25% compared with NH₄NO₃ as nitrogen source.