Pilot scale conversion of wheat straw to ethanol via simultaneous saccharification and fermentation (original) (raw)
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Applied Microbiology and Biotechnology, 2011
Ethanol production by recombinant Escherichia coli strain FBR5 from dilute acid pretreated wheat straw (WS) by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) was studied. The yield of total sugars from dilute acid (0.5% H 2 SO 4 ) pretreated (160°C, 10 min) and enzymatically saccharified (pH 5.0, 45°C, 72 h) WS (86 g/l) was 50.0± 1.4 g/l. The hydrolyzate contained 1,184±19 mg furfural and 161±1 mg hydroxymethyl furfural per liter. The recombinant E. coli FBR5 could not grow at all at pH controlled at 4.5 to 6.5 in the non-abated wheat straw hydrolyzate (WSH) at 35°C. However, it produced 21.9± 0.3 g ethanol from non-abated WSH (total sugars, 44.1± 0.4 g/l) in 90 h including the lag time of 24 h at controlled pH 7.0 and 35°C. The bioabatement of WS was performed by growing Coniochaeta ligniaria NRRL 30616 in the liquid portion of the pretreated WS aerobically at pH 6.5 and 30°C for 15 h. The bacterium produced 21.6±0.5 g ethanol per liter in 40 h from the bioabated enzymatically saccharified WSH (total sugars, 44.1±0.4 g) at pH 6.0. It produced 24.9±0.3 g ethanol in 96 h and 26.7±0.0 g ethanol in 72 h per liter from bioabated WSH by batch SSF and fed-batch SSF, respectively. SSF offered a distinct advantage over SHF with respect to reducing total time required to produce ethanol from the bioabated WS. Also, fed-batch SSF performed better than the batch SSF with respect to shortening the time requirement and increase in ethanol yield.
Bioresource Technology, 2011
Ethanol production by a recombinant bacterium from wheat straw (WS) at high solid loading by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) was studied. The yield of total sugars from dilute acid pretreated WS (150 g/L) after enzymatic saccharification was 86.3 ± 1.5 g/L. The pretreated WS was bio-abated by growing a fungal strain aerobically in the liquid portion for 16 h. The recombinant Escherichia coli strain FBR5 produced 41.1 ± 1.1 g ethanol/L from nonabated WS hydrolyzate (total sugars, 86.6 ± 0.3 g/L) in 168 h at pH 7.0 and 35°C. The bacterium produced 41.8 ± 0.0 g ethanol/L in 120 h from the bioabated WS by SHF. It produced 41.6 ± 0.7 g ethanol/L in 120 h from bioabated WS by fed-batch SSF. This is the first report of the production of above 4% ethanol from a lignocellulosic hydrolyzate by the recombinant bacterium.
Ethanol production by recombinant Escherichia coli strain FBR5 from dilute acid pretreated wheat straw (WS) by separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) was studied. The yield of total sugars from dilute acid (0.5% H 2 SO 4 ) pretreated (160°C, 10 min) and enzymatically saccharified (pH 5.0, 45°C, 72 h) WS (86 g/l) was 50.0± 1.4 g/l. The hydrolyzate contained 1,184±19 mg furfural and 161±1 mg hydroxymethyl furfural per liter. The recombinant E. coli FBR5 could not grow at all at pH controlled at 4.5 to 6.5 in the non-abated wheat straw hydrolyzate (WSH) at 35°C. However, it produced 21.9± 0.3 g ethanol from non-abated WSH (total sugars, 44.1± 0.4 g/l) in 90 h including the lag time of 24 h at controlled pH 7.0 and 35°C. The bioabatement of WS was performed by growing Coniochaeta ligniaria NRRL 30616 in the liquid portion of the pretreated WS aerobically at pH 6.5 and 30°C for 15 h. The bacterium produced 21.6±0.5 g ethanol per liter in 40 h from the bioabated enzymatically saccharified WSH (total sugars, 44.1±0.4 g) at pH 6.0. It produced 24.9±0.3 g ethanol in 96 h and 26.7±0.0 g ethanol in 72 h per liter from bioabated WSH by batch SSF and fed-batch SSF, respectively. SSF offered a distinct advantage over SHF with respect to reducing total time required to produce ethanol from the bioabated WS. Also, fed-batch SSF performed better than the batch SSF with respect to shortening the time requirement and increase in ethanol yield.
Production of Biocellulosic Ethanol from Wheat Straw
Wheat straw is an abundant lignocellulosic feedstock in many parts of the world, and has been selected for producing ethanol in an economically feasible manner. It contains a mixture of sugars (hexoses and pentoses). Two-stage acid hydrolysis was carried out with concentrates of perchloric acid, using wheat straw. The hydrolysate was concentrated by vacuum evaporation to increase the concentration of fermentable sugars, and was detoxified by over-liming to decrease the concentration of fermentation inhibitors. After two-stage acid hydrolysis, the sugars and the inhibitors were measured. The ethanol yields obtained from by converting hexoses and pentoses in the hydrolysate with the co-culture of Saccharomyces cerevisiae and Pichia stipites were higher than the ethanol yields produced with a monoculture of S. cerevisiae. Various conditions for hysdrolysis and fermentation were investigated. The ethanol concentration was 11.42 g/l in 42 h of incubation, with a yield of 0.475 g/g, productivity of 0.272 g/l ·h, and fermentation efficiency of 92.955 %, using a co-culture of Saccharomyces cerevisiae and Pichia stipites.
Applied Microbiology and Biotechnology, 2011
Continuous production of ethanol from alkaline peroxide pretreated and enzymatically saccharified wheat straw hydrolysate by ethanologenic recombinant Escherichia coli strain FBR5 was investigated under various conditions at controlled pH 6.5 and 35°C. The strain FBR5 was chosen because of its ability to ferment both hexose and pentose sugars under semi-anaerobic conditions without using antibiotics. The average ethanol produced from the available sugars (21.9-47.8 g/L) ranged from 8.8 to 17.3 g/L (0.28-0.45 g/g available sugars, 0.31-0.48 g/g sugar consumed) with ethanol productivity of 0.27-0.78 gl −1 h −1 in a set of 14 continuous culture (CC) runs (16-105 days). During these CC runs, no loss of ethanol productivity was observed. This is the first report on the continuous production of ethanol by the recombinant bacterium from a lignocellulosic hydrolysate.
Biodiversitas, 2019
Fractions of sulfuric acid-pretreated wheat straw, i.e. solid, liquid, and a mixture of liquid and solid were used as substrates in simultaneous saccharification and fermentation (SSF) process to produce ethanol. The bioconversion was performed by Monascus purpureus CBS 109.07 and Fusarium venenatum ATCC 20334. The highest ethanol yields from solid, liquid and a mixture of solid and liquid fractions by M. purpureus CBS 109.07 were 0.36, 0.41, and 0.37 g/g glucose, respectively. The corresponding values by F. venenatum ATCC 20334 were 0.21, 0.54, 0.35 g/g glucose, respectively.
Fungal pretreatment: An alternative in second-generation ethanol from wheat straw
Bioresource Technology, 2011
The potential of a fungal pretreatment combined with a mild alkali treatment to replace or complement current physico-chemical methods for ethanol production from wheat straw has been investigated. Changes in substrate composition, secretion of ligninolytic enzymes, enzymatic hydrolysis efficiency and ethanol yield after 7, 14 and 21 days of solid-state fermentation were evaluated. Most fungi degraded lignin with variable selectivity degrees, although only eight of them improved sugar recovery compared to untreated samples. Glucose yield after 21 days of pretreatment with Poria subvermispora and Irpex lacteus reached 69% and 66% of cellulose available in the wheat straw, respectively, with an ethanol yield of 62% in both cases. Conversions from glucose to ethanol reached around 90%, showing that no inhibitors were generated during this pretreatment. No close correlations were found between ligninolytic enzymes production and sugar yields.
Bioconversion of wheat straw lignocellulosic sugars to ethanol by recombinant Escherichia coli
Journal of Renewable and Sustainable Energy, 2012
Potential of bioethanol production from Nypa fruticans sap by a newly isolated yeast Lachancea fermentati J. Renewable Sustainable Energy 4, 033110 Synchronization of fluid-dynamics related and physiological time scales and algal biomass production in thin flatplate bioreactors J. Appl. Phys. 111, 034904 Potential for ethanol production from conservation reserve program lands in Oregon J. Renewable Sustainable Energy 3, 063102 Automating fruit fly Drosophila embryo injection for high throughput transgenic studies Rev. Sci. Instrum. 79, 013705 (2008) Additional information on J. Renewable Sustainable Energy
2018
Bioethanol is a potentially safe and renewable alternate source of energy. However, ethanol production from value added food and feedstock has not shown growth as estimated. Of late, the second generation processes of production of ethanol, such as from lignocellulosic biomass out of agricultural/domestic waste, has been gaining considerable momentum. Here, we attempted optimizing the conditions of physiochemical pretreatment as well as fermentation process using wheat straw by Pichia stipitis NCIM 3498 (now known as Schefferomyces stipitis). We have also studied the influence of process variables, such as incubation temperature, inoculum concentration and different nutrients, on ethanol production. Pulverized wheat straw consists of 32±0.31% cellulose, 48±0.37% hemicellulose and 17±0.15% lignin on dry solid (DS) basis. Wheat straw delignified with 1% HNO 3 , yielded 11.54% xylose and 1.54% glucose under steam explosion [15 psi (121°C) for 60 min], with a hydrolytic efficiency of 59.56%. Simultaneous Saccharification and Fermentation (SSF) of pretreated wheat straw by crude cellulose (produced by Trichoderma reesei NCIM 1052) and S. stipitis were investigated in the present study. Important process variables for ethanol production from pretreated wheat straw were optimized using response surface methodology (RSM) based on central composite design (CCD) experiments. A three level CCD experiments with central and axial points was used to develop a statistical model for optimization of process variables viz. incubation temperature (30, 32 and 34°C) X1, inoculum level (2, 4 and 6%) X2 and nutrients (1/2/3) X3. Data obtained from RSM on ethanol production were subjected to the analysis of variance (ANOVA), analyzed using a second order polynomial equation, and contour plots were used to study the interactions among three relevant variables of the fermentation process. The fermentation experiments were carried out at flask level. The processing parameters setup for reaching a maximum response for ethanol production was obtained when applying the optimum values for temperature (34°C), inoculum level (6%) and fermentation medium (ammonium sulphate, KH 2 PO 4 , peptone and yeast extract) for S. stipitis. Maximum ethanol concentration 7.15 g/L was obtained after 72 h from S. stipitis at the optimized process conditions in anaerobic batch fermentation.