Comparison of Acidified and Antibiotic-supplemented Potato Dextrose Agar from Three Manufacturers for its Capacity to Recover Fungi from Foods.

Six lots of potato dextrose agar (PDA) obtained from three manufacturers were compared for their capacity to recover yeasts and molds from 10 foods. Each lot was tested in two forms, viz., at pH 3.5 and at pH 5.6. The media at pH 5.6 contained 100 ppm each of chloramphenicol and chlortetracycline-HCI. Overall. no single source or lot of PDA was superior to others for enumerating fungi. However, results confirm earlier reports from another laboratory that antibiotic-supplemented PDA performs better than does acidified PDA for determining fungal populations in foodstuffs.