Construction Of Commercial Strain Producing Itaconic Acid From Raw Starch By Protoplast Fusion

Interspecific protoplast fusion between Aspergillus terreus T-730, an itaconic acid producer, and Aspergillus niger Ni-5k, a glucoamylase producer, was done to breed new mold producing itaconic acid from starch. The Ni-5 strain was induced with Antibiotic-A,which became a drugresistant strain Ni-5k. The protoplast of Ni-5k was inactived after treated by 20W UV, 35 minute. The mycelium of T-730 and Ni-5k were treated with mixed enzyme which including cellulase. Snailase and Lysozyme. The protoplast yield of T-730 and Ni-5k was 3. 2+107/ml and 3.8+106/ml under the optimum conditions. Using 30% PEG6000 as a fusogenic agent, the fusion frequency between T-730 and Ni-5k was 1. 18+10-5. The stabilities of some fusants (F3, F9, Fll) obtained were confined by successive subcultures. One of the stable fusants F3, morphologically resembled T-730, and produced maximally 40. 9mg/ml itaconic acid from raw corn starch(10%) at 6 days of cultivation. The productivity of itaconic acid from raw corn starch was 66. 5% of that of T-730 from sucrose(10%).