Kinetic study of batch and fed-batch enzymatic saccharification of pretreated substrate and subsequent fermentation to ethanol

Abstract

BackgroundEnzymatic hydrolysis, the rate limiting step in the process development for biofuel, is always hampered by its low sugar concentration. High solid enzymatic saccharification could solve this problem but has several other drawbacks such as low rate of reaction. In the present study we have attempted to enhance the concentration of sugars in enzymatic hydrolysate of delignified Prosopis juliflora, using a fed-batch enzymatic hydrolysis approach.ResultsThe enzymatic hydrolysis was carried out at elevated solid loading up to 20% (w/v) and a comparison kinetics of batch and fed-batch enzymatic hydrolysis was carried out using kinetic regimes. Under batch mode, the actual sugar concentration values at 20% initial substrate consistency were found deviated from the predicted values and the maximum sugar concentration obtained was 80.78 g/L. Fed-batch strategy was implemented to enhance the final sugar concentration to 127 g/L. The batch and fed-batch enzymatic hydrolysates were fermented with Saccharomyces cerevisiae and ethanol production of 34.78 g/L and 52.83 g/L, respectively, were achieved. Furthermore, model simulations showed that higher insoluble solids in the feed resulted in both smaller reactor volume and shorter residence time.ConclusionFed-batch enzymatic hydrolysis is an efficient procedure for enhancing the sugar concentration in the hydrolysate. Restricting the process to suitable kinetic regimes could result in higher conversion rates.

Comparison of Ethanol Yield Between Separate and Simultaneous Hydrolysis and Ethanol Fermentation of Formic- Fractionated Sugarcane Bagasse

“…The process thus can achieve high ethanol content and high ethanol recovery [7,17,18]. One of drawbacks of the SSF was in this process; the pretreated biomass was hydrolyzed at the same temperature with the ethanol fermentation.…”

“…The glucose concentration in the SSF was accumulated to 93.53 g/L at 24 h, and decreased sharply afterwards showing yeast activity converting glucose to ethanol. That also may suggest the SSF can be started earlier to avoid accumulation of the glucose higher than 50 g/L in the reaction [12,17,18]. In the SHF process, the glucose concentration in the reaction dropped to zero after 48h of fermentation (Fig.…”

Modelo estructural para evaluar el estrés en profesionales que orientan a la niñez en programas de formación inclusiva

“…Situación que incide en el logro de metas institucionales, dado que según Gupta et al (2012) el estrés llevó a profesionales a la insatisfacción en el trabajo, al bajo compromiso y al ausentismo, y acorde a presencia de enfermedades psicosomáticas, a solicitudes de reemplazo. Varios estudios indicaron que los factores personales de trabajadores que los llevaron a sufrir estrés fueron edad, género, correlatos fisiológicos, afrontamiento, cambios de personalidad.…”

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

“…Enzyme kinetics is influenced by the interplay of a number of factors, whose effect should be assessed together. The main parameters that affect enzymatic hydrolysis of lignocellulose biomass are enzyme and substrate concentrations and hydrolysis conditions such pH, temperature and time (Bansal et al 2009;Gan et al 2003;Gupta et al 2012). However, taking into account all these factors at once is a complex task, especially for heterogeneous substrates like apple pomace, a waste product from the apple juice industry.…”