Producción de bioetanol utilizando biomasa de un cultivo mixto de microalgas como materia prima

Abstract

The biotechnological potential of microalgae in biofuels production continues to be a promising alternative to face the current energy crisis. This research project aimed to use the biomass of a mixed microalgae culture to produce bioethanol, for which the biomass production using industrial by-products as additional sources of carbon in the culture media was evaluated, and the optimal conditions for the acid hydrolysis of the carbohydrates contained in the microalgal biomass were determined. The mixotrophic cultures, composed of carbon dioxide and cheese whey or ethylene glycol as carbon sources, allowed the generation of higher biomass yields (1.38 and 0.60 milligrams per milliliter) in comparison with the autotrophic culture using carbon dioxide solely (0.50 milligrams per milliliter). Regarding the acid hydrolysis of carbohydrates, the higher release of reducing sugars per dry biomass (0.27 milligrams per milligram) was obtained using 2.0 percent volume-volume sulfuric acid. Additionally, it was determined that it is possible to obtain a higher amount of reducing sugars from the biomass obtained in the culture medium supplemented with ethylene glycol (0.30 milligrams per milligram). Finally, ethanol was produced by Saccharomyces cerevisiae at a concentration per dry biomass of 0.35 milligrams per milligram with a process yield of 82 percent from the fermentation of the sugars present in the biomass hydrolysate obtained from the culture with ethylene glycol. The results support the use of the biomass of the microalgae consortium as an efficient alternative to produce third-generation bioethanol.