Full Length Research Paper

Combined amino acids modulation with H₂O₂ stress for glutathione overproduction in Candida utilis

Bin Wang¹, Guobin Liang¹, Quanfa Zhou¹, Jianghui Xie² and Yiwei Mo²*

¹School of Chemistry and Environmental Engineering, Jiangsu Teachers University of Technology, Changzhou 213001, China.

²South Subtropical Crop Research Institute, Chinese Academy of Tropical Agricultural Science, Zhanjiang 524091, China.

*Corresponding author. E-mail: moyiwei08@yahoo.cn.  Tel: +86-759-2859272.

Fax: +86-759-2858168.

Abbreviations: PEP, Phosphoenolpyruvate; GSH, reduced glutathione; GSSG, oxidized glutathione; DCW, dry cell weight; HCD, high cell density cultivation.

Accepted 22 July, 2010

   Abstract

Strategies of amino acids addition coupled with H₂O₂ 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.

Key words: Amino acids, glutathione (GSH), high cell density (HCD) cultivation, Candida utilis, H₂O₂ stresses.