Combined amino acids modulation with H 2 O 2 stress for glutathione overproduction in Candida utilis

Abstract

Strategies of amino acids addition coupled with H 2 O 2 stresses were developed for glutathione (GSH) overproduction in high cell density (HCD) cultivation of Candida utilis . Based on the fact that glycine shows two functions of promoting cells growth as well as GSH production, precursor amino acids modulations of feeding glycine at 4 mmol/l/h at exponential phase and adding precursor amino acids (glutamic acid 42 mmol/l, glycine 40 mmol/l, and cysteine 36 mmol/) at stationary phase were conducted. As a result, cell density reached 114.8 g/l at 45 h and glutathione yield of 2136 mg/l was achieved at 60 h, which was 12.5 and 90.2% higher than the control, respectively. Furthermore, the novel strategies of amino acids modulation combined with H2O2 additions (24 mmol/l at 21 h, 26 mmol/l at 29 h, 28 mmol/l at 37 h and 30 mmol/l at 45 h) were adopted to maximize glutathione production. Final glutathione yield reached 2448 mg/l after 60 h cultivation, suggesting the strategies developed as being feasible for GSH overproduction. Keywords: Amino acids, glutathione (GSH), high cell density (HCD) cultivation, Candida utilis , H 2 O 2 stresses African Journal of Biotechnology Vol. 9(33), pp. 5399-5406, 16 August, 2010