Optimization of a low-cost defined medium for alcoholic fermentation - A case study for potential application in bioethanol production from industrial wastewters

COMELLI, RN; SELUY, LG; ISLA, MA

NEW BIOTECHNOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 33 p. 107 - 115

1871-6784

In bioethanol production processes,the media composition has an impact on product concentration, yields and the overallprocess economics. The main purpose of this research was to develop a low-costmineral-based supplement for successful alcoholic fermentation in an attempt toprovide an economically feasible alternative to produce bioethanol from novelsources, e.g., sugary industrial wastewaters. Statistical experimental designswere used to select essential nutrients for yeast fermentation, and its optimalconcentrations were estimated by Response Surface Methodology. Fermentationswere performed on synthetic media inoculated with 2.0 g/L of yeast, and theevolution of biomass, sugar, ethanol, CO2 and glycerol weremonitored over time.A mix of salts [10.6 g/L (NH4)2HPO4;6.4 g/L MgSO4.7H2O and 7.5 mg/L ZnSO4.7H2O]was found to be optimal. It led to the complete fermentation of the sugars inless than 12 h with an average ethanol yield of 0.42 gethanol/gsugar.A general C-balance indicated that no carbonaceous compounds different frombiomass, ethanol, CO2 or glycerol were produced in significantamounts in the fermentation process. Similar results were obtained when softdrink wastewaters were tested to evaluate the potential industrial applicationof this supplement. The ethanol yields were very close to those obtained whenyeast extract was used as the supplement, but the optimized mineral-basedmedium is six times cheaper, which favorably impacts the process economics andmakes this supplement more attractive from an industrial viewpoint.