Bioprocess optimization of glutathione production by Saccharomyces boulardii: biochemical characterization of glutathione peroxidase

The well-known probiotic GRAS Saccharomyces boulardii (CNCM I-745) was used for the first time to produce glutathione (GSH). culture conditions affecting GSH biosynthesis were screened using a Plackett–Burman design (PBD). Analyzing regression coefficients 12 tested variables, yeast extract, glucose, peptone, cysteine, temperature and agitation rate had positive significant effect on production with maximum yeild 192 mg/L. impact of kinetics adding cysteine investigated in 19 experiments during growth course (0–36 h), yield (235 mg/L) obtained by addition after 8 h post-inoculation. most variables further explored at five levels central composite rotatable (CCRD), giving (552 mg/L). Using baffled flasks, increased 730 mg/L, i.e., 1.32-fold increment. two rate-limiting genes “γ-glutamyl synthetase (GSH1) GSH-synthetase (GSH2)” amplified sequenced validate biosynthetic potency S. boulardii. sequences showed 99% similarity GSH1 GSH2 cerevisiae. Glutathione peroxidase purified characterized from molecular mass subunit structure 80 kDa 35 as revealed native SDS-PAGE, ensuring its homodimeric identity. activity GPx reduced 2.5-fold upon demetallization confirming metalloproteinic strongly inhibited hydroxylamine DTNB, implication surface lysine residues enzyme active site domains.