Abstract
Improvement of the α-tocopherol productivity of Euglena gracilis Z was achieved by derivation of an analog-resistant strain. Among various compounds tested, β-2-thienylalanine was selected as the best inhibitor for derivation of high α-tocopherol-producing strains.
A number of β-2-thienylalanine-resistant strains were obtained on UV irradiation with or without streptomycin treatment, and also on spontaneous mutation. One strain, S-T1, produced 4 times as much α-tocopherol as the wild type strain.
As the result of optimization of the culture conditions, strain S-T1 produced 48.4 mg per 1 of culture broth or 1.8 mg per gram of dry cell weight (DCW) of α-tocopherol intracellularly. The addition of homogentisate and ethanol increased the production to 130.3 mg per 1 or 4.8 mg per gram of DCW. Finally, a high amount of α-tocopherol, 180.4mg per 1 of 6.3 mg per gram of DCW, was obtained with the feeding of glucose during the cultivation.
