Abstract
Cheese whey is a liquid effluent obtained from the cheese manufacturing process, presenting a high volumetric production and high organic loads related to its lactose content. The aim of this research was to increase the productivity of ABE fermentation with the bacterial strain Clostridium beijerinckii CECT 508, when using nanofiltered sheep cheese whey as a substrate. Thermal sterilization of the whey was essential to avoid the proliferation of lactic acid bacteria. An experimental design including Plackett-Burman and Response Surface Methodology (RSM) was applied to figure out which additional nutrients were necessary for the fermentation process and their optimum concentrations. For this specific whey, it was established that 1 g/L yeast extract, 5 g/L CaCO3, 0.019 g/L FeSO4·7H2O, 0.2 g/L MgSO4·7H2O and 2.1 g/L NH4Cl needed to be added. Under optimal nutrient conditions, the highest butanol production (9.11 g/L) was obtained with an initial lactose concentration of 57 g/L; achieving 49% lactose consumption and 0.311 g/g YB/L yield. However, the best lactose consumption rate (87%) was recorded for lactose initial concentrations of 30 g/L, which also allowed satisfactory fermentation values (8.51 g/L butanol and 0.328 g/g YB/L yield). On the other hand, the best YB/L yields (0.428 g/g; which is close to the theoretical value) were obtained for initial lactose concentrations of 40 g/L, attaining a value of 52% lactose consumption and 8.91 g/L butanol. Therefore, the ABE fermentation could be a feasible solution to treat cheese whey and remove lactose, obtaining acceptable amounts of butanol.
