Lipid and carotenoid production by oleaginous red yeast Rhodotorula glutinis cultivated on brewery effluents

Abstract

This study investigated the production of microbial lipids for biodiesel production and high-value carotenoids by Rhodotorula glutinis combined with the use of brewery wastewater as carbon source for three treatments: (raw wastewater) WWraw, (glucose supplemented raw wastewater) WWglu and a (synthetic sugar medium) WWsynth. The collected brewery effluents showed high contents of sugars (maltose 24.34 g L−1; glucose 5.77 g L−1), but the low utilization of maltose led to a limitation of carbon in WWraw and WWglu. Since nitrogen was still available, carbon was channeled into cell growth instead of lipid formation, reaching an overall biomass production of 5.22 g L−1, 7.38 g L−1, and 9.55 g L−1, respectively. Carotenoids were synthesized in all treatments with total average carotenoid contents between 0.6 and 1.2 mg L−1 and with high proportions of β-carotene (∼50%) in the wastewater treatments. Suboptimal culture conditions (pH; aeration) have been identified as obstacles for higher lipid and carotenoid yields. Nevertheless, brewery wastewaters can be considered as carbon source for microbial fermentation, since they can be assumed to be an adequate source of nitrogen and other nutrients, whereas the utilization of maltose needs to be increased to achieve considerable amounts of lipid and carotenoid production.