Microbial production of citric acid from salad oil

Strain CCU-U2-N4-41 was derived from a wild strain of yeast CCU-087. This strain can produce large amounts of citric acid from salad oil. The optimal medium for citric acid production is one liter of medium containing salad oil 100 g, yeast extract 2.0 g, CH3COONH4 3.0 g, KH2PO4 5.0 g, MgSO4 500 ppm, 1 ppm each of MnSO(4).5 H2O and CuSO(4).2 H2O, pH: 7.0. The optimal culture conditions are: temperature: 28 degrees C; agitation: 110 rpm; 100 mL medium in 500-mL Hinton flask; 1.5% CaCO3 added after 12 hr incubation. With 96 hr cultivation 71.2 g/L of citric acid can be produced. Citric acid produced was compared with authentic citric acid by melting point determination, IR, NMR and Mass. From the spectra, it was found that they were identical.