Abstract
The parent strain A. oryzae A-59 produce unsaturated fatty acids extracellularly. Using an UV irradiation process on the conidium, it mutated and obtained the mutant U-4 that was proven to be superior in secretion. The secretion property of the mutant U-4 stabilized. The extracellular unsaturated fatty acids were not only triglyceride, but also diglyceride, monoglyceride and free fatty acid. The mutant U-4, when cultured with 3.0% palmitic acid, produced 17.4mg/g dry cell of unsaturated fatty acids extracellularly, which was approximately 1.8 times more than that of the parent strain. In addition, the accumulation of fatty acid increased as the C/N ratio of the medium went up. The extracellular production of unsaturated fatty acids was a maximum at the C/N ratio of 6.0.
