• Microbiology and Biotechnology Letters
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• v.26 no.3
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• pp.213-220
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• 1998

An ATP regeneration system was used for the production of glutathione which was synthesized by a sequential action of ${\gamma}$-glutamyl-cysteine synthetase and glutathione synthetase. The synthetases above were produced in the recombinant E. coli (TG1/pDG7) with the highest specific production yield of 31 mg glutathione/g wet cell. Bakers yeast was considered to have economically a better ATP regeneration system although the glutathione production yield was lower than that of acetate kinase. It was also observed that the ATP regeneration system of bakers yeast was superior to that of Saccharomyces cerevisiae ATCC24858. The yield of glutathione production with bakers yeast was 36% with the ATP concentration of 5 mM. To avoid the cysteine limitation during the early phase of glutatione production, an extra cysteine was added at 2 hours after reaction and the production yield increased 1.91 times. The effectiveness of bakers yeast as an ATP regeneration system was proved by several sets of extra feeding experiments. The product inhibition by glutathione above 14 mM was also observed.

• KSBB Journal
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• v.14 no.4
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• pp.445-451
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• 1999

Glutathione production was carried out using mixed cells of E. coli TG1/pDG7 $\alpha$ and bakers yeast in an Aerated Slurry Bioreactor. Glutathione-producing enzymes were stable for 34 hours, yielding 4.6 mM glutathione in suspension reaction. Glutahione production with high density mixed cells was studied as a function of flow rate in an Aereated Slurry Bioreactor. Glutathione concentration was higher than that in suspension reaction for 32 hours at the substrate feeding rate of 5.2 mL/hr with cell recycle in continuous Aerated Slurry Bioreactor. It was for 42 hours at 2.6 mL/hr and 22 hours at 5.2 mL/hr without cell recycle. Glutahione productivity was 25.7 mg/g wet $cell{\cdot}hr$ at the substrate feeding rate of 10.4 mL/hr with cell recycle, but 5.28 mg/g wet $cell{\cdot}hr$ at 5.2 mL/hr and 1.65 mg/g wet $cell{\cdot}hr$ at 2.6 mL/hr without cell recycle. Effective production time increased from 25 to 45 hours, by using a surfactant, tween 80. As a purfing gas, nitrogen was tested instead of air to avoid a possible oxidizing effect on glutathione-producing enzymes, resulting in the increase of effective production time to 40 hours.