Selection of yeast strain and fermentation conditions for high-yield ethanol production from lactose and concentrated whey

A total of 65 yeast strains were screened for their ability to grow and ferment lactose in a standard DURHAM tube test at 30 degrees C. Based on the kinetic parameters for lactose and whey lactose fermentations in shake flask cultures, the strain Candida pseudotropicalis 65 was chosen for further studies. Some of the cultural parameters affecting ethanolic fermentations on lactose were standardized. At an initial lactose concentration of 100-120 g/l in the medium containing concentrated whey or lactose, at 40 degrees C and within 48 h, the selected strain reached an ethanol concentration of 41-59 g/l, an ethanol productivity of 1.3-3.0 g/l/h, a lactose consumption of 99%, an ethanol yield 0.4-0.49 g/g and a biomass yield of 0.027 g/g.