Optimization of agro-industrial coproducts (molasses and cassava wastewater) for the simultaneous production of lipids and carotenoids by Rhodotorula mucilaginosa

A major obstacle in the bioproduction of metabolites of industrial interest is the high cost of the culture medium. Obtaining two bioproducts simultaneously (lipids and carotenoids) by Rhodotorula mucilaginosa can solve part of this problem. However, reconciling two metabolites is a challenge since the nutritional needs of yeasts for one metabolite (lipid) are often not the same as those for another (carotenoids). The use of co-products can minimize the cost of the process when they substitute a commercial medium. And the success of simultaneous bioproduction can be achieved using a strategy of experimental planning that combines sugarcane molasses (25 g/L to 55 g/L) and cassava wastewater (20 g/L to 50 g/L), optimizing and adding value to the process. In this study, 7.94 g/L of lipids were produced with an accumulation in dry mass of 48.14% and 2958.32 μg/L (168.08 μg/g) of volumetric and specific carotenoids concentration. In addition, in an experiment using ammonium sulfate (3 g/L) as an activator, there was an increase of 94.46% and 81.16% in the production of specific and volumetric carotenoids, respectively. In the gas chromatographic analysis, oleic (73.67%), palmitic (20.23%) and linoleic (4.01%) acids were found. Our studies demonstrated the strategic viability of simultaneously obtaining lipids and carotenoids through an ideal combination of co-products from cheap renewable sources, making it possible to reduce the costs of processing in bioreactors. •Lipids and carotenoids were obtained simultaneously with an optimal concentration of molasses and cassava wastewater.•Yeast reduced the organic matter present in the agro-industrial culture medium by 82.78%.•The activator [3 g/L of (NH4)2SO4] increased the amount of carotenoids produced by 81.16%.•Oleic acid (73.67%) was the main lipid found in the yeast.