Enzymatic hydrolysis optimization to ethanol production by simultaneous saccharification and fermentation

Abstract

There is tremendous interest in using agro-industrial wastes, such as cellulignin, as starting materials for the production of fuels and chemicals. Cellulignin are the solids, which result from the acid hydrolysis of the sugarcane bagasse. The objective of this work was to optimize the enzymatic hydrolysis of the cellulose fraction of cellulignin, and to study its fermentation to ethanol using Saccharomyces cerevisiae. Cellulose conversion was optimized using response surface methods with pH, enzyme loading, solid percentage, and temperature as factor variables. The optimum conditions that maximized the conversion of cellulose to glucose, calculated from the initial dried weight of pretreated cellulignin, (43 degrees C, 2%, and 24.4 FPU/g of pretreated cellulignin) such as the glucose concentration (47 degrees C, 10%, and 25.6 FPU/g of pretreated cellulignin) were found. The desirability function was used to find conditions that optimize both, conversion to glucose and glucose concentration (47 degrees C, 10%, and 25.9 FPU/g of pretreated cellulignin). The resulting enzymatic hydrolyzate was fermented yielding a final ethanol concentration of 30.0 g/L, in only 10 h, and reaching a volumetric productivity of 3.0 g/L x h, which is close to the values obtained in the conventional ethanol fermentation of sugar cane juice (5.0-8.0 g/L x h) in Brazil.

Using an artificial neural network to predict the optimal conditions for enzymatic hydrolysis of apple pomace

“…It has been reported by some researchers that enzyme concentration had a more significant impact than substrate concentration on the release of sugars, which was in agreement with results obtained in this study (Mussatto et al 2008;Rosgaard et al 2007;Vasquez et al 2007). …”

“…The results indicated that hydrolysis of apple pomace was influenced by the interaction of different parameters, though to a different magnitude. The obtained results were similar to what was reported by Vasquez et al (2007) on hydrolysis of sugarcane bagasse: that enzyme loading had the highest effect followed by temperature, when they considered the effect of pH, percentage solids, enzyme loading and temperature. There was less significant effect on hydrolysis as a result of interaction of factors and pH had less effect compared with other variables in the range considered.…”

Effect of Cellulase, Substrate Concentrations, and Configuration Processes on Cellulosic Ethanol Production from Pretreated Arundo donax

“…Interestingly, in both conditions (37 and 50 °C), the final ethanol content was higher than that achievable from the glucose concentration obtained by pre-hydrolysis. This result could have been due to the reactivation of the cellulase enzymes after the conversion of glucose by the yeast during the fermentation step (Vásquez et al 2007).…”

Evaluation of Composition, Characterization and Enzymatic Hydrolysis of Pretreated Sugar Cane Bagasse

“…The mixture was also subjected to a temperature of 121 °C for 30 min (Vasquez et al, 2007). The pH of the mixture was adjusted to 7.0 using HCl after the reaction.…”