Process for obtaining copper-enriched cells of Saccharomyces cerevisiae

The research was aimed at obtaining copper-enriched cells of Saccharomyces cerevisiae, developing an efficient metal delivery system for human nutrition and therapeutic treatments. To produce glutathione (GSH)–copper conjugates, four samples of commercial baker's yeasts (S. cerevisiae) were employed in biotransformation trials with copper acetate. GSH production was found variable, ranging from 0.15 to 1.2% cell dw. Trials carried out with copper-adapted cells resulted in GSH and conjugate limited biosynthesis. The highest copper conjugate level (1.7% dw) was instead obtained in experiments set up by employing not adapted cells. Cell disruption by sonication and subsequent analysis by atomic absorption evidenced the presence of very interesting amount of intracellular copper, 1.8 ± 0.2 mg/g cell dw (i.e. 28 μmol copper/g cell dw). The proposed procedure can be considered an interesting opportunity to further the range of application of yeast cells culture, for the set up of a copper delivery system for therapeutic treatments.