Ethanol Production Using Agroindustrial Residues as Fermentation Substrates by Kluyveromyces marxianus

Abstract

The search for renewable energies has been stimulating the production of ethanol, which can be produced by using agro-industrial waste as substrates for fermentation. The aim of this investigation was to use whey permeate and sugarcane molasses to obtain bioethanol by submerged fermentation using the thermotolerant yeast Kluyveromyces marxianus. The concentrations of ethanol and sugars were determined by high performance liquid chromatography. The highest ethanol concentration of 50.04 g/L was obtained with the optimized medium with 100, 6.26, and 6.26 g/L of lactose (from whey permeate), yeast extract, and (NH₄)₂SO₄, respectively. The association of whey permeate (WP) with sugarcane molasses (SM) in the fermentation medium led to higher concentrations of ethanol (49.11 g/L) in the proportion of 80% WP and 20% SM. Therefore, the use of the agroindustrial residues in fermentation suggests a viable industrial application and can generate advantages for being low-cost by-products.