Aspergillus ochraceus production of 5,6-dihydropenicillic acid in culture and foods

Abstract

The production of 5,6-dihydropenicillic acid (DHPA) and penicillic acid (PA) by Aspergillus ochraceus was studied. DHPA has been revealed to be genotoxic in the Drosophila DNA-repair test in our previous report. The two compounds were produced by various type strains of A. ochraceus and related strains of Aipergillus in nutrient cultures. When A. ochraceus cells were inoculated into nutrient medium, PA was rapidly produced followed by a steady increase of DHPA and a decrease in the PA level. On the contrary, A. ochraceus produced almost exclusively PA in potato dextrose agar medium, which is low in nutrients. A. ochraceus cells produced DHPA when inoculated into grain, especially in rice flour at 20 to 24°C, and the DHPA level increased as the incubation was prolonged. These results suggested that PA was converted to DHPA under highly nutritive conditions. In vitro mutagenicity tests, the Ames test and the umu test, showed that DHPA was not mutagenic. Copyright ©, International Association of Milk, Food and Environmental Sanitarians.