Bioconversion of spent coffee grounds into carotenoids and other valuable metabolites by selected red yeast strains

•A spent coffee ground has been utilized for yeast biomass production.•The cultivation was carried out in shaking flasks and laboratory bioreactor.•Dried spent coffee ground contains approximately 15% of oil fraction.•Sporobolomyces roseus showed the highest potential for the pigment accumulation.•The introduction of pulse feeding strategy remarkably improved biomass production.

Spent coffee grounds (SCG) represent the main coffee industry residues with a great potential to be reutilized in various biotechnological processes. In this study, several carotenogenic yeasts strains were exploited for the production of vitamin-enriched biomass, cultivating in SCG-based media. The fermentation was firstly carried out in Erlenmeyer flasks in order to select the best biomass and pigment producer. Among four tested strains, Sporobolomyces roseus showed the highest potential for the accumulation of carotenoids. Maximum pigment concentration and yield was obtained when cultivating in SCG-based media, 12.59 mg l−1 and 1.26 mg g−1, respectively. Comparing both, the batch and the fed-batch cultivation modes, the strategy of sequential addition of pre-concentrated SCG media in the bioreactor gave higher biomass yield (maximum 41 g l−1 during 41–48 h after the beginning of fermentation). Thus, SCG can be considered as potentially promising industrial waste stream for economically feasible production of enriched yeasts biomass.