Simultaneous saccharification and fermentation process of different cellulosic substrates using a recombinant Saccharomyces cerevisiae harbouring the β-glucosidase gene

Abstract

In Brazil, the production of ethanol from sugarcane produces large amounts of lignocellulosic residues (bagasse and straw), which have been driving research and development for the production of second generation ethanol. In the present work, a recombinant Saccharomyces cerevisiae strain expressing the β-glucosidase gene from Humicola grisea was used for ethanol production from three different cellulosic sources by simultaneous saccharification and fermentation. Initially, a enzymatic pre-hydrolysis step was done with a solid:liquid ratio of 1:4, and an enzymatic load of 25 filter paper activity (FPU).g -1 of cellulosic substrate. Using sugarcane bagasse pretreated cellulignin, crystalline cellulose and carboxymethyl cellulose, 51.7 g L -1 , 41.7 g L -1 and 13.8 g L -1 of ethanol was obtained, respectively, at the end of 55 hrs of *Corresponding author fermentation. The highest ethanol productivity (0.94 g L -1 hrs -1 ) was achieved using sugarcane bagasse pretreated cellulignin. The use of a recombinant S. cerevisiae led to extremely low glucose concentrations when compared to other works reported in literature.

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.…”

Sugarcane bagasse and leaves: foreseeable biomass of biofuel and bio‐products

“…Afterwards, the treated solution was used for SSF. Ferreira et al 35 carried out SSF for ethanol production using a recombinant S. cerevisiae harboring a β-glucosidase gene wileyonlinelibrary.com/jctb and obtained 60 g L −1 ethanol production. However, studies on consolidated bioprocesses using SB for ethanol production have yet to be conducted.…”

Trichoderma harzianum IOC-4038: A Promising Strain for the Production of a Cellulolytic Complex with Significant β-Glucosidase Activity from Sugarcane Bagasse Cellulignin

“…Such characteristic allows the crude enzyme extract produced by T. harzianum to be used in simultaneous saccharification and fermentation (SSF) processes, which are commonly conducted at 37°C and pH 5.0-5.5 [21,22]. In these conditions, the relative FPase, endoglucanase, and β-glucosidase activities (compared to the maximum correspondent activities observed during These results show that the extract produced by T. harzianum presents great potential for application to ethanol and other chemical production using processes that require complete cellulose hydrolysis at mild conditions.…”

“…At 37°C, all enzyme activities, except FPase from A. niger and β-glucosidase from T. reesei (data not shown), maintained at least 80% of their initial activity after 23 h of incubation. From a general perspective, the results observed in the present study indicate that the cellulolytic complex produced by T. harzianum presents potential for application to the complete hydrolysis of cellulose, especially at mild temperature, such as that used in SSF processes [21,22], while the high thermal stability of endoglucanase from A. niger suggests that this group of enzymes can be used in processes which require high temperatures, such as those found in the textile industry [24].…”