Co-production of γ -glutamylcysteine and glutathione by mutant strain Saccharomyces cerevisiae FC-3 and its kinetic analysis

Co-production of γ -glutamylcysteine (γ -GC) and glutathione (GSH) by a novel mutant strain Saccharomyces cerevisiae FC-3 and its kinetic analysis were investigated. The strain could produce γ -GC and GSH with high yields (4.22 and 14.3 mg/g-DCW, respectively) in batch submerged cultures. Effects of medium components and cultivation conditions on cell growth and the contents of intracellular γ -GC and GSH were examined. Results show that 2% (w/v) sucrose and 2.5% (w/v) yeast extract are the best carbon and nitrogen sources, respectively, and supplement of three amino acids (glycine, cysteine and glutamate), each at 0.08% (w/v), in the medium could enhance γ -GC and GSH production. In addition, optimal operating conditions are at the initial pH value of 7.0, 30 °C and 200 rev/min. Moreover, results obtained from kinetic analyses reveal that γ -GC production is mixed-type growth associated, but GSH production is growth-associated. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)