Fig. 4

Glutathione production by S. cerevisiae GCIΔGLR1 strains over-expressing ERV1 and its mutant genes. a Intracellular GSH content; b intracellular GSSG content; c intracellular GSH and GSSG content; d intracellular GSSG ratio to GSH and GSSG. All fermentation for glutathione production were separately performed three times. Data are presented as the mean ± standard deviation (n = 3). Asterisks indicate statistical significances determined by Student’s t test. One asterisk indicates a p value smaller than 0.05 (p < 0.05). Two asterisks indicate a p value smaller than 0.01 (p < 0.01)