comparação entre processos em SHF e em SSF de bagaço de cana-de-açúcar para a produção de etanol por Saccharomyces cerevisiae

Souza

Appl Microbiol Biotechnol

et al. 2014

The conversion of lignocellulose into fermentable sugars is considered a promising alternative for increasing ethanol production. Higher fermentation yield has been achieved through the process of simultaneous saccharification and fermentation (SSF). In this study, a comparison was performed between the yeast species Saccharomyces cerevisiae and Kluyveromyces marxianus for their potential use in SSF process. Three strains of S. cerevisiae were evaluated: two are widely used in the Brazilian ethanol industry (CAT-1 and PE-2), and one has been isolated based on its capacity to grow and ferment at 42 °C (LBM-1). In addition, we used thermotolerant strains of K. marxianus. Two strains were obtained from biological collections, ATCC 8554 and CCT 4086, and one strain was isolated based on its fermentative capacity (UFV-3). SSF experiments revealed that S. cerevisiae industrial strains (CAT-1 and PE-2) have the potential to produce cellulosic ethanol once ethanol had presented yields similar to yields from thermotolerant strains. The industrial strains are more tolerant to ethanol and had already been adapted to industrial conditions. Moreover, the study shows that although the K. marxianus strains have fermentative capacities similar to strains of S. cerevisiae, they have low tolerance to ethanol. This characteristic is an important target for enhancing the performance of this yeast in ethanol production.

Section: Discussionsupporting

confidence: 81%

Physiological characterization of thermotolerant yeast for cellulosic ethanol production

Souza

Appl Microbiol Biotechnol

et al. 2014

“…The residual glucose content was similar for all samples (1.9 to 2.7 g L -1 ), irrespective of pretreatment type. The residual glucose concentrations of this study were lower than those observed by Santos et al (2010) in a similar study considering 16 h presaccharification and 10 h SSSF for delignified bagasse. Souza et al (2012) found no residual glucose after 10 h SSSF.…”

Section: Assessment Of Bioethanol Productioncontrasting

confidence: 84%

“…Sugarcane bagasse and eucalyptus prepared using acid pretreatments produced only 3.6 g L -1 and 1.3 g L -1 ethanol, respectively. Santos et al (2010) achieved an ethanol concentration for sugarcane bagasse almost threefold higher than that obtained in the present study by performing 40 h SSSF (from which 16 h were pure presaccharification); however, these authors used alkaline pretreatment for bagasse delignification, which most likely favored the enzymatic hydrolysis by improving the cellulose accessibility. The volumetric productivity of ethanol achieved by these aforementioned authors for bagasse (0.30 g L -1 h-1) was higher than the observed in the present study after hydrothermal pretreatment (0.08 g L -1 h -1 ), but lower than the observed after acid pretreatment (0.36 g L -1 h -1 ).…”

Section: Assessment Of Bioethanol Productioncontrasting

confidence: 67%

“…Several lignocellulosic feedstocks have been investigated for bioethanol cellobiose to glucose; and 2) simultaneous saccharification and fermentation (SSF), in which enzymes (for saccharification) and yeast (for fermentation) are kept in the same reactor, and the reactions for enzymatic hydrolysis and fermentation occur at the same time, resulting in ethanol production, mainly from the glucose released. The presaccharification performed in SSSF is important to supply glucose in concentrations high enough to activate the yeast at the beginning of fermentation (Santos et al 2010). Presaccharification improves ethanol yield and reduces enzyme inhibition (such as glucose and cellobiose in high concentration) and fermentation time (Gonçalves et al 2014;Baeyens et al 2015;Cotana et al 2015).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Hydrothermal and Acid Pretreatments Improve Ethanol Production from Lignocellulosic Biomasses

2017

a Hydrothermal and acid pretreatments using different acid charges (1.5%, 3.0%, and 4.5% H2SO4) were proposed for eucalyptus, sugarcane bagasse, and sugarcane straw prior to their bioconversion into ethanol using the semi-simultaneous saccharification and fermentation (SSSF) process. The hydrothermal and acid pretreatments were efficient for hemicelluloses removal from eucalyptus (63 to 96%), bagasse (25 to 98%), and straw (23 to 95%) and to remove a substantial amount of lignin from eucalyptus (10 to 34%) and bagasse (10 to 27%). During pretreatments, pseudo-extractives and pseudo-lignin were generated from biomasses. The SSSF was performed in pretreated biomasses using 24 h presaccharification followed by an additional 10 h of simultaneous saccharification and fermentation (SSF). With hydrothermal pretreatment, the eucalyptus presented the highest ethanol production, but only low values for SSSF parameters were obtained, as follows: ethanol yield ). On the other hand, using acid pretreatment, the straw (pretreated using 4.5% H2SO4) presented the highest ethanol production among the biomasses, assessed based on ethanol yield (0.056 gethanol/gbiomass), volumetric productivity of ethanol ).

“…EH was performed with 4% (w/v) of delignified pretreated solid of CFM, in an Erlenmeyer flask with a volume of 48 mL at 50 C, using the enzymatic kit of Cellic CTec 2 and Cellic HTec 2 with an enzyme loading of 30 FPU, 75 CBU and 130 IU per gram of pretreated solid, respectively, in 50 mM sodium citrate buffer with 0.02% (w/v) sodium azide to prevent microbial growth. The agitation was maintained at 150 rpm for 96 h. The samples were taken at 6 h intervals for the first 12 h and 12 h intervals until a total time of 96 h [24,25]. All determinations were performed in duplicate.…”

Section: Enzymatic Hydrolysismentioning

confidence: 99%

Bioethanol production by Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis from delignified coconut fibre mature and lignin extraction according to biorefinery concept

et al. 2016

In search to increase the offer of liquid, clean, renewable and sustainable energy in the world energy matrix, the use of lignocellulosic materials (LCMs) for bioethanol production arises as a valuable alternative. The objective of this work was to analyze and compare the performance of Saccharomyces cerevisiae, Pichia stipitis and Zymomonas mobilis in the production of bioethanol from coconut fibre mature (CFM) using different strategies: simultaneous saccharification and fermentation (SSF) and semisimultaneous saccharification and fermentation (SSSF). The CFM was pretreated by hydrothermal pretreatment catalyzed with sodium hydroxide (HPCSH). The pretreated CFM was characterized by X-ray diffractometry and SEM, and the lignin recovered in the liquid phase by FTIR and TGA. After the HPCSH pretreatment (2.5% (v/v) sodium hydroxide at 180 C for 30 min), the cellulose content was 56.44%, while the hemicellulose and lignin were reduced 69.04% and 89.13%, respectively. Following pretreatment, the obtained cellulosic fraction was submitted to SSF and SSSF. Pichia stipitis allowed for the highest ethanol yield e 90.18% e in SSSF, 91.17% and 91.03% were obtained with Saccharomyces cerevisiae and Zymomonas mobilis, respectively. It may be concluded that the selection of the most efficient microorganism for the obtention of high bioethanol production yields from cellulose pretreated by HPCSH depends on the operational strategy used and this pretreatment is an interesting alternative for add value of coconut fibre mature compounds (lignin, phenolics) being in accordance with the biorefinery concept.