Elevated glutathione production by adding precursor amino acids coupled with ATP in high cell density cultivation ofCandida utilis

Abstract

Three precursor amino acids and adenosine triphosphate (ATP) are necessary for fermentative production of glutathione. In this study, our aims were to develop a strategy to enhance glutathione production by adding three precursor amino acids coupled with ATP in high cell density (HCD) cultivation of Candida utilis. A high-glutathione yeast strain, C. utilis WSH 02-08, was used in this study. Whole fermentative process for glutathione production was divided into two phases of cell growth and glutathione synthesis. Cells concentration was increased by HCD cultivation. Meanwhile, intracellular glutathione content was enhanced by the addition of three precursor amino acids. Concentrations of three precursor amino acids added at stationary phase were optimized by response surface methodology. Moreover, the addition of ATP 15 h after the addition of the three amino acids can further enhance glutathione production. Based on aforementioned phenomenon, a strategy of adding three precursor amino acids coupled with ATP was developed to enhance glutathione production. Without the addition of three precursor amino acids and the ATP, a total glutathione of 1123 mg l(-1) was achieved after 60-h cultivation. In comparison, addition of three precursor amino acid counterparts resulted in a total glutathione of 1841 mg l(-1). Moreover, by adding amino acids combined with ATP, a total glutathione of 2043 mg l(-1) was achieved after 72-h cultivation, increased by 81.9% and 11%, respectively, as compared with the control and the one without ATP addition. This is the first report on investigating changes of the intracellular three precursor amino acids and ATP, and gamma-glutamylcysteine synthase activity in HCD cultivation of C. utilis for glutathione production. A strategy of combining addition of three precursor amino acids with ATP was developed to enhance glutathione production in C. utilis.