Pilot scale pretreatment of wheat straw and comparative evaluation of commercial enzyme preparations for biomass saccharification and fermentation

Agrawal, Ruchi; Satlewal, Alok; Gaur, Ruchi; Mathur, Anshu S.; Kumar, Ravindra; Gupta, Ravi P.; Tuli, Deepak K.

doi:10.1016/j.bej.2015.02.018

Cited by 68 publications

(30 citation statements)

References 42 publications

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“…Hydrolysate samples were taken periodically and analyzed for cellobiose and total phenols using Waters' HPLC with Aminex HPX-87P column (Bio-Rad, United States) coupled with refractive index detector (Agrawal et al, 2018). Milli-Q water was used as a mobile phase at a flow rate of 0.6 ml/min, with a column temperature of 75 • C (Agrawal et al, 2015b). The total phenols were estimated by Folin-Ciocalteu method (Sanchez-Rangel et al, 2013).…”

Section: Cellobiose and Total Phenols Estimationsmentioning

confidence: 99%

“…During the dilute acid pretreatment, hemicellulose is hydrolyzed into monomeric sugars, that is, xylose, arabinose, galactose, glucose, and mannose, with alternations in the lignin structure (Agrawal et al, 2015b(Agrawal et al, , 2017aSkiba et al, 2017). This, in turn, increases the pore volume and surface area of the substrate, improving the enzyme accessibility.…”

Section: Pretreatment and Chemical Composition Of Rice Strawmentioning

confidence: 99%

“…However, the E/S reduces considerably when the whole enzyme is added initially, while the fresh substrate is added stepwise. In addition to this, the enzyme also binds non-productively with the lignin and might also get deactivated in the presence of inhibitors generated after pretreatment and a high operational temperature (50 • C) (Agrawal et al, 2015b). Thus, there is a high probability of prolonged enzyme exposure with inhibitors when the entire enzyme was added initially as compared with the enzyme splitting (Ganesh et al, 2000).…”

Section: Substrate Plus Enzyme Splitting: Optimization Of the Sizes Fmentioning

confidence: 99%

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Improved Enzymatic Hydrolysis of Pilot Scale Pretreated Rice Straw at High Total Solids Loading

et al. 2018

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Enzymatic hydrolysis at high solids loading has the potential to reduce both capital and operational expenditures. Here, pretreatment of rice straw (PRS) with dilute acid was carried out at a pilot scale (250 kg per day) at 162 • C for 10 min and 0.35% acid concentration, followed by enzymatic hydrolysis at different total solids loadings. It showed that although the total sugar concentration increased from 48 to 132 g/l, glucan conversion reduced by 27% (84-66.2%) with increasing solids from 5 to 20% in batch mode. Therefore, two different fed-batch approaches were evaluated to improve the glucan conversion by the sequential addition of a substrate and/or enzyme. At 20% solid loadings and a 3 filter paper units/g enzyme dosage, the highest glucan conversion obtained was 66% after 30 h of hydrolysis in batch mode. However, in an optimized fed-batch approach, the glucan yield was improved to 70% by simply dividing the substrate feeding into three batches, that is, 50% at 0 h, 25% each after 4 h, and 8 h of hydrolysis reaction. The addition of surfactant (Ecosurf E6) further improved the conversion to 72% after 30 h. The role of critical factors, that is, inhibitors, enzyme-lignin binding, and viscosity, was investigated during the course of hydrolysis in the batch and fed-batch approaches. This study suggests a sustainable approach for improved hydrolysis at high solids loadings by fine-tuning a simple process.

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Section: Cellobiose and Total Phenols Estimationsmentioning

confidence: 99%

Section: Pretreatment and Chemical Composition Of Rice Strawmentioning

confidence: 99%

Section: Substrate Plus Enzyme Splitting: Optimization Of the Sizes Fmentioning

confidence: 99%

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Improved Enzymatic Hydrolysis of Pilot Scale Pretreated Rice Straw at High Total Solids Loading

et al. 2018

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“…This necessitates the addition of higher levels of -d-glucosidase to hydrolyse cellobiose than would be necessary in the absence of product inhibition (Bohlin et al, 2013). A simple solution is simultaneous saccharification and fermentation wherein glucose is rapidly removed; however, the low temperatures at which current commercial fermentative organisms operate do not take full advantage of the higher temperature optimum of the hydrolytic enzymes and the trade-off is typically not in favour of this strategy, particularly with more recent commercial enzyme preparations (Ask et al, 2012;Wirawan et al, 2012;Cannella & Jørgensen, 2014;Agrawal et al, 2015). Another possible solution is the use of certain GH1 family -d-glucosidases with a much higher apparent K i for glucose; however, many if not most of these have poor activity on cellobiose, although exceptions have been reported (Pei et al, 2012;Cota et al, 2015).…”

Section: The Importance Of B-d-glucosidases In Industrial Biotechnologymentioning

confidence: 99%

Three-dimensional structures of two heavily N-glycosylatedAspergillussp. family GH3 β-D-glucosidases

Agirre

Ariza

Offen

et al. 2016

Acta Cryst Sect D Struct Biol

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The industrial conversion of cellulosic plant biomass into useful products such as biofuels is a major societal goal. These technologies harness diverse plant degrading enzymes, classical exo-and endo-acting cellulases and, increasingly, cellulose-active lytic polysaccharide monooxygenases, to deconstruct the recalcitrant -d-linked polysaccharide. A major drawback with this process is that the exo-acting cellobiohydrolases suffer from severe inhibition from their cellobiose product. -d-Glucosidases are therefore important for liberating glucose from cellobiose and thereby relieving limiting product inhibition. Here, the three-dimensional structures of two industrially important family GH3 -d-glucosidases from Aspergillus fumigatus and A. oryzae, solved by molecular replacement and refined at 1.95 Å resolution, are reported. Both enzymes, which share 78% sequence identity, display a three-domain structure with the catalytic domain at the interface, as originally shown for barley -d-glucan exohydrolase, the first three-dimensional structure solved from glycoside hydrolase family GH3. Both enzymes show extensive N-glycosylation, with only a few external sites being truncated to a single GlcNAc molecule. Those glycans N-linked to the core of the structure are identified purely as highmannose trees, and establish multiple hydrogen bonds between their sugar components and adjacent protein side chains. The extensive glycans pose special problems for crystallographic refinement, and new techniques and protocols were developed especially for this work. These protocols ensured that all of the d-pyranosides in the glycosylation trees were modelled in the preferred minimum-energy 4 C 1 chair conformation and should be of general application to refinements of other crystal structures containing O-or N-glycosylation. The Aspergillus GH3 structures, in light of other recent three-dimensional structures, provide insight into fungal -d-glucosidases and provide a platform on which to inform and inspire new generations of variant enzymes for industrial application.

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“…Recently, Agrawal, et al39 have reported that 90% PWS hydrolysis was obtained with CL enzyme aer 48 h at 30 mg protein per g biomass. a The synergistic values as found in reaction mixture (rxn) are reported as U ml À1 of rxn while, the theoretical additive values corresponding to the protein are depicted within brackets.…”

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confidence: 99%

Improved saccharification of pilot-scale acid pretreated wheat straw by exploiting the synergistic behavior of lignocellulose degrading enzymes

et al. 2015

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Requirement of high enzyme dosage for lignocellulosic biomass hydrolysis is one of the challenges for the viability of the second generation bioethanol technology. Here, an optimal enzyme mixture was developed by partially replacing the cellulase proportion with accessory enzymes (b-glucosidase, xylanase, pectinase, laccase) and its hydrolytic performance was compared with different commercial counterparts for the saccharification of pretreated wheat straw (PWS) using a 250 kg per day continuous pilot plant. Maximum degree of synergism was observed with xylanase followed by pectinase, laccase, and bglucosidase. The statistically optimized enzyme mixture enhanced hydrolysis by 51.23% and 40.66% in 6 h and 24 h, respectively. This study elucidates that presence of even small amount of oligomers and cellobiose pose a strong inhibition for the enzymes. Therefore, development of an optimal enzyme formulation is a sustainable approach to reduce overall enzyme loading for biomass saccharification.

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Pilot scale pretreatment of wheat straw and comparative evaluation of commercial enzyme preparations for biomass saccharification and fermentation

Cited by 68 publications

References 42 publications

Improved Enzymatic Hydrolysis of Pilot Scale Pretreated Rice Straw at High Total Solids Loading

Improved Enzymatic Hydrolysis of Pilot Scale Pretreated Rice Straw at High Total Solids Loading

Three-dimensional structures of two heavily N-glycosylatedAspergillussp. family GH3 β-D-glucosidases

Improved saccharification of pilot-scale acid pretreated wheat straw by exploiting the synergistic behavior of lignocellulose degrading enzymes

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