A comparative account of glucose yields and bioethanol production from separate and simultaneous saccharification and fermentation processes at high solids loading with variable PEG concentration

Kadhum, Haider Jawad; Mahapatra, Durga Madhab; Murthy, Ganti S.

doi:10.1016/j.biortech.2019.03.060

Cited by 46 publications

(12 citation statements)

References 44 publications

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“…glucose when hydrothermally pretreated SCB was depolymerized with Cellic CTec2 dosed at 20.92 mg protein g -1 glucan. The present results are far superior to recently published data, where the same enzyme at 20 mg protein g -1 glucan yielded 176 ± 5.9 g L -1 glucose from 30% dilute acid pretreated wheat straw after 96 h (Kadhum et al, 2019). Kim et al (2019) reported the release of 157.5 g L -1 fermentable sugars after 120 h when Cellic CTec2 (30 FPUg -1 glucan) mediated hydrolysis was conducted with 30% pretreated oak.…”

Section: Effect Of Naoh Concentration On Delignification Of Scb At Hi...contrasting

confidence: 88%

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

et al. 2021

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In an enzymatically driven lignocellulosic biorefinery, pretreatment and hydrolysis modules are the two most significant cost contributors for obtaining high gravity sugar solutions. The present study aimed to reduce the use of alkali and Cellic CTec2 during the bioprocessing of sugarcane bagasse (SCB). Later its impact on the overall process economics and the environment was evaluated. During pretreatment, solid loading of 15% (w/w) and use of 2% (w/v) sodium hydroxide at 121C for 30 min emerged as an optimum strategy. It resulted in >65% delignification of SCB, retaining ≥ 90 % and 65 % of glucan and xylan fraction, respectively, in the pretreated biomass. Two approaches were evaluated in parallel to minimize the requirement of this commercial cellulase enzyme blend. The first strategy involved its partial replacement with an in-house enzyme cocktail by blending. The second route was performing hydrolysis with reduced loadings of cellulase enzyme blend above its optimum temperature, which gave more promising results. Hydrolysis of 20% alkali pretreated SCB with cellulase enzyme blend dosed at 15 mg protein g-1 glucan led to 84.13 ± 1 and 83.5 ± 2.3% glucan and xylan conversion yields respectively in 48h at 52.5C. The filtrate and wash fraction contained ≥ 165 and ≥ 65 g L-1 sugar monomers representing glucose and xylose. However, in both the fractions >75%, sugar accounted for glucose. The techno-economic analysis revealed that the sugar production cost from SCB was 1.32 US$/kg, with the optimized bioprocess. Environmental impact study showed that the process contributed to 1.57 kg CO2 eq in terms of climate change.

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Section: Effect Of Naoh Concentration On Delignification Of Scb At Hi...contrasting

confidence: 88%

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

et al. 2021

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“…On the contrary, xylose yield increased proportionally with the surfactant concentration. The highest xylose concentration of 5.34 g L −1 was obtained at 25 g L −1 of Tween 80 after 72 h. Low monosaccharides yields were probably due to inefficient xylanase activity of enzyme preparation and the presence of remaining lignin [26,42]. Most of the studies reported in the literature have been performed at low substrate loading or high enzyme loading that support the high substrate conversions rates.…”

Section: Effect Of Tween 80 On Enzyme Hydrolysis and Lipid Productionmentioning

confidence: 88%

“…The addition of Tween 80 improved glucose and xylose yield (21% and 16%, respectively) and increased the hydrolysis rate. Considering the low price of Tween 80, supplementing an enzyme reaction with this surfactant could also raise the sugar yield and improve economic performance [42].…”

Section: Effect Of Tween 80 On Enzyme Hydrolysis and Lipid Productionmentioning

confidence: 99%

Strategies for Improvement of Lipid Production by Yeast Trichosporon oleaginosus from Lignocellulosic Biomass

Grubišić

Mihajlovski

Gruičić

et al. 2021

JoF

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Microbial lipids have similar fatty acid composition to plant oils, and therefore, are considered as an alternative feedstock for biodiesel production. Oleaginous yeasts accumulate considerable amounts of lipids intracellularly during growth on low-cost renewable feedstocks such as lignocellulosic biomass. In this study, we cultivated yeast Trichosporon oleaginosus on hydrolysate of alkaline pretreated corn cobs. Different process configurations were evaluated and compared, including separate hydrolysis and fermentation (SHF) with cellulase recycle and simultaneous saccharification and fermentation (SSF) in batch and fed-batch mode. At low enzyme loading, the highest lipid concentration of 26.74 g L−1 was reached in fed-batch SSF fed with 2.5% (g g−1) substrate. Batch SHF was conducted for four rounds with recycling the cellulase adsorbed on unhydrolyzed lignocellulosic biomass. Thirty percent of cellulase saving was achieved for rounds 2–4 without compromising productivity and lipid yield. The addition of Tween 80 to lignocellulosic slurry improved the hydrolysis rate of structural carbohydrates in pretreated lignocellulosic biomass. Furthermore, supplementing the growth medium with Tween 80 improved lipid yield and productivity without affecting yeast growth. Oleaginous yeast T. oleaginosus is a promising strain for the sustainable and efficient production of lipids from renewable lignocellulosic feedstock.

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“…The chemical-free hydrothermal pretreatment combined with mechanical milling has been introduced to increase reducing sugar yields . Moreover, the high solids processing (>15%) is favored by industry to increase sugar and product concentrations and reduce operating costs. , The fed-batch hydrolysis and surfactants have been applied in high solids biorefineries to improve mass transfer for securing high productivity . The 50% solids process combining hydrothermal pretreatment, mechanical refining, and fed-batch enzymatic hydrolysis has been scaled up and achieved a maximum sugar titer of 230 g/L …”

Section: Introductionmentioning

confidence: 99%

Conversion of High-Solids Hydrothermally Pretreated Bioenergy Sorghum to Lipids and Ethanol Using Yeast Cultures

Dien

Liu

Thompson

et al. 2021

ACS Sustainable Chem. Eng.

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Glucose and xylose are the major sugars present in cellulosic hydrolysates. The cellulosic sugars can be used for the production of platform chemicals. In this study, productions of lipid and ethanol by yeasts were compared for concentrated bioenergy sorghum syrup. Bioenergy sorghum was hydrothermally pretreated at 50% w/w solids in a continuous industrial reactor and sequentially mechanically refined using a burr mill to improve biomass accessibility for hydrolysis. Fed-batch enzymatic hydrolysis was conducted with 50% w/v solids loading and cellulase cocktail (50 FPU/g biomass) to achieve 230 g/L sugar concentration. Various strains of Rhodosporidium toruloides were evaluated for converting sugars into lipids, and strain Y-6987 had the highest lipid titer (9.2 g/L). The lipid titer was improved to 19.0 g/L by implementing a two-stage culture scheme, where the first stage was optimized for yeast growth and the second for lipid production. For ethanol production, the engineered Saccharomyces cerevisiae SR8ΔADH6 was utilized to coferment glucose and xylose. Ethanol fermentation was optimized for media nutrients (YP, YNB/urea, and urea), cellulosic sugar concentration, and sulfite conditioning to maximize the ethanol concentration from sorghum syrups. Fermentation of 70% v/v concentrated hydrolysate conditioned with sulfite produces 50.1 g/L ethanol from 141 g/L of sugars.

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A comparative account of glucose yields and bioethanol production from separate and simultaneous saccharification and fermentation processes at high solids loading with variable PEG concentration

Cited by 46 publications

References 44 publications

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

Cost reduction approaches for fermentable sugar production from sugarcane bagasse and its impact on techno-economics and the environment

Strategies for Improvement of Lipid Production by Yeast Trichosporon oleaginosus from Lignocellulosic Biomass

Conversion of High-Solids Hydrothermally Pretreated Bioenergy Sorghum to Lipids and Ethanol Using Yeast Cultures

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