Coproduction of Glutathione and 5-Aminolevulinic Acid by Saccharomyces cerevisiae NMZ-2 on Spent Coffee Grounds.

Large amounts of spent coffee grounds (SCGs) are generated daily around the world. SCGs can be partly used for fertilizer production by composting through multiple microbial fermentations. In the coffee biorefinery, an attractive way to add value to the SCGs fertilizer is by producing additional biostimulants. In this study, glutathione (GSH) and 5-aminolevulinic acid (5-ALA), biostimulants for agriculture, were coproduced by fermentation of a yeast, Saccharomyces cerevisiae NMZ-2, with spent coffee grounds extract (SCGE). The addition of SCGE promoted the growth of this strain and the production of GSH and 5-ALA. This study indicated that SCGE contained carbon and nitrogen sources and minerals for the S. cerevisiae NMZ-2. Controlling the amount of glycine could regulate the ratio of GSH and 5-ALA production. Biostimulants containing a favorable ratio of GSH and 5-ALA produced by the S. cerevisiae NMZ-2 using SCGE would be applicable in a coffee biorefinery.