The influence of presaccharification, fermentation temperature and yeast strain on ethanol production from sugarcane bagasse

Abstract

Ethanol can be produced from cellulosic biomass in a process known as simultaneous saccharification and fermentation (SSF). The presence of yeast together with the cellulolytic enzyme complex reduces the accumulation of sugars within the reactor, increasing the ethanol yield and saccharification rate. This paper reports the isolation of Saccharomyces cerevisiae LBM-1, a strain capable of growth at 42 °C. In addition, S. cerevisiae LBM-1 and Kluyveromyces marxianus UFV-3 were able to ferment sugar cane bagasse in SSF processes at 37 and 42 °C. Higher ethanol yields were observed when fermentation was initiated after presaccharification at 50°C than at 37 or 42° C. Furthermore, the volumetric productivity of fermentation increased with presaccharification time, from 0.43 g/L/h at 0 h to 1.79 g/L/h after 72 h of presaccharification. The results suggest that the use of thermotolerant yeasts and a presaccharification stage are key to increasing yields in this process.

Hydrothermal and Acid Pretreatments Improve Ethanol Production from Lignocellulosic Biomasses

“…The commercial cellulase preparation Celluclast 1.5 L was used for enzymatic hydrolysis. In a 125 mL Erlenmeyer flask, 4 g of pretreated biomass were suspended in 50.0 mL of citrate buffer (50 mM, pH 4.8) and supplemented with 15 Filter Paper Units (FPU) of enzyme per gram of substrate (1.4 mL) (Souza et al 2012). The flask was capped and incubated in a shaker at 50 °C for 24 h and 180 rpm agitation according to Carvalho et al (2016).…”

“…In a 125-mL Erlenmeyer flask, 4 g of pretreated biomass were suspended in 50. (Souza et al 2012). The flask was capped and incubated in a shaker at 50 °C and 180 rpm for 24 h.…”

“…5 and 6, respectively (Souza et al 2012), (5) where YE/B is the ethanol yield (gethanol/gbiomass), EtOHf and EtOHi are the final and initial ethanol mass (g), respectively, (measured in samples collected from fermentation medium), and Biomass is total mass of biomass (g) used for SSSF. (6) In Eq.…”

Combined Biogas and Bioethanol Production: Opportunities and Challenges for Industrial Application

“…The viability of cell populations, the specific rate of fermentation and the sugar uptake rate are all directly related to the desired medium condition [37]. Similarly both process configuration and yeast strain play a fundamental role in the definition of fementation yields [38][39][40][41], along with the feedstock characteristics. [36].…”

Improved Ethanol Production Based on High Solids Fed-Batch Simultaneous Saccharification and Fermentation with Alkali-Pretreated Sugarcane Bagasse

“…However, SSF is constrained by the typically suboptimal conditions for hydrolysis and fermentation, and limited by the available carbon sources for the microbes. These problems are reduced by adding a pre-hydrolysis step into SSF, which allows the enzymatic phase to operate at optimal temperatures and yields more ethanol than other processes (Öhgren et al 2006;Ko et al 2009;Souza et al 2012;Tan et al 2013).…”