The impact of alkali pretreatment and post-pretreatment conditioning on the surface properties of rice straw affecting cellulose accessibility to cellulases

Karuna, Nardrapee; Zhang, Lu; Walton, Jeffrey H.; Couturier, Marie; Öztop, Mecit Halil; Master, Emma R.; McCarthy, Michael J.; Jeoh, Tina

doi:10.1016/j.biortech.2014.05.122

Cited by 49 publications

(54 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The adsorption capacity of the isolated lignins was measured by adding cellulases solution (diluted Celluclast) at different concentrations to the same amount of lignin [35]. In 2 mL centrifuge tubes, 1.0 mL of the cellulase solution (from 0.05 to 0.4 mg/mL) was added to 20 mg of lignin.…”

Section: Methodsmentioning

confidence: 99%

Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin

Siqueira

Arantes

Saddler

et al. 2017

Biotechnol Biofuels

108

View full text Add to dashboard Cite

BackgroundThe effectiveness of the enzymatic hydrolysis of cellulose in plant cell wall is strongly influenced by the access of enzymes to cellulose, which is at least in part limited by the presence of lignin. Although physicochemical treatments preceding the enzymatic catalysis significantly overcome this recalcitrance, the residual lignin can still play a role in the process. Lignin is suggested to act as a barrier, hindering cellulose and limiting the access of the enzymes. It can also unspecifically bind cellulases, reducing the amount of enzymes available to act on cellulose. However, the limiting role of the lignin present in pretreated sugarcane bagasses has not been fully understood yet.ResultsA set of sugarcane bagasses pretreated by five leading pretreatment technologies was created and used to assess their accessibility and the unproductive binding capacity of the resulting lignins. Steam explosion and alkaline sulfite pretreatments resulted in more accessible substrates, with approximately 90% of the cellulose hydrolyzed using high enzyme loadings. Enzymatic hydrolysis of alkaline-treated (NaOH) and steam-exploded sugarcane bagasses were strongly affected by unproductive binding at the lowest enzyme loading tested. Analysis of the extracted lignins confirmed the superior binding capacity of these lignins. Sulfite-based pretreatments (alkaline sulfite and acid sulfite) resulted in lignins with lower binding capacities compared to the analogue pretreatments without sulfite (alkaline and acidic). Strong acid groups present in sulfite-based pretreated substrates, attributed to sulfonated lignins, corroborated the lower binding capacities of the lignin present in these substrates. A more advanced enzyme preparation (Cellic CTec3) was shown to be less affected by unproductive binding at low enzyme loading.ConclusionsPretreatments that increase the accessibility and modify the lignin are necessary in order to decrease the protein binding capacity. The search for the called weak lignin-binding enzymes is of major importance if hydrolysis with low enzyme loadings is the goal for economically viable processes.

show abstract

Section: Methodsmentioning

confidence: 99%

Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin

Siqueira

Arantes

Saddler

et al. 2017

Biotechnol Biofuels

108

View full text Add to dashboard Cite

show abstract

“…Total bound enzyme in the retentate was measured based on previous methods (Jeoh et al, 2007;Karuna et al, 2014). Briefly, 150 mL of the resuspended retentate of each sample was transferred to 96-well black plates and read in a multi-mode microplate reader (Synergy 4, BioTek Instrument, Inc., Winooski, VT) at excitation and emission wavelengths of 490 and 525 nm, respectively (Invitrogen, Thermo Fisher Scientific Inc., Sunnyvale, CA).…”

Section: Bound Enzyme Determinationmentioning

confidence: 99%

The productive cellulase binding capacity of cellulosic substrates

Karuna

Jeoh

2016

Biotech & Bioengineering

Self Cite

View full text Add to dashboard Cite

Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydrolyze glycosidic bonds, the "accessibility of cellulose to cellulases" is considered to be a reaction limiting property of cellulose. We have defined the accessibility of cellulose to cellulases as the productive binding capacity of cellulose, that is, the concentration of productive binding sites on cellulose that are accessible for binding and hydrolysis by cellulases. Productive cellulase binding to cellulose results in hydrolysis and can be quantified by measuring hydrolysis rates. In this study, we measured the productive Trichoderma reesei Cel7A (TrCel7A) binding capacity of five cellulosic substrates from different sources and processing histories. Swollen filter paper and bacterial cellulose had higher productive binding capacities of ∼6 µmol/g while filter paper, microcrystalline cellulose, and algal cellulose had lower productive binding capacities of ∼3 µmol/g. Swelling and regenerating filter paper using phosphoric acid increased the initial accessibility of the reducing ends to TrCel7A from 4 to 6 µmol/g. Moreover, this increase in initial productive binding capacity accounted in large part for the difference in the overall digestibility between filter paper and swollen filter paper. We further demonstrated that an understanding of how the productive binding capacity declines over the course of the hydrolysis reaction has the potential to predict overall saccharification time courses. Biotechnol. Bioeng. 2017;114: 533-542. © 2016 Wiley Periodicals, Inc.

show abstract

“…Time domain spin‐spin ( T 2 ) LFNMR relaxometry techniques have been found useful to characterize water present in biomass. This technique classifies water in various sample types, and relates to both chemical and physical properties of biomass and cellulose . Using LFNMR relaxometry a relationship between water constraint, as expressed by T 2 relaxation times of the solvent, and enzymatic hydrolysis yields of cellulose was found for soluble monosaccharides and for various insoluble cell wall polymers .…”

Section: Introductionmentioning

confidence: 99%

“…This technique classifies water in various sample types, and relates to both chemical and physical properties of biomass and cellulose. [30][31][32][33][34][35] Using LFNMR relaxometry a relationship between water constraint, as expressed by T 2 relaxation times of the solvent, and enzymatic hydrolysis yields of cellulose was found for soluble monosaccharides 36 and for various insoluble cell wall polymers. 37,38 Based on the research published so far on the interrelations between plant biomass digestibility and water availability, quantification and characterization of the interaction between biomass and water could be a feasible path toward a better understanding of the generic mechanisms underlying biomass recalcitrance.…”

Section: Introductionmentioning

confidence: 99%

Biomass‐water interactions correlate to recalcitrance and are intensified by pretreatment: An investigation of water constraint and retention in pretreated spruce using low field NMR and water retention value techniques

Weiss

Thygesen

Felby

et al. 2016

Biotechnology Progress

View full text Add to dashboard Cite

The underlying mechanisms of the recalcitrance of biomass to enzymatic deconstruction are still not fully understood, and this hampers the development of biomass based fuels and chemicals. With water being necessary for most biological processes, it is suggested that interactions between water and biomass may be key to understanding and controlling biomass recalcitrance. This study investigates the correlation between biomass recalcitrance and the constraint and retention of water by the biomass, using SO pretreated spruce, a common feedstock for lignocellulosic biofuel production, as a substrate to evaluate this relationship. The water retention value (WRV) of the pretreated materials was measured, and water constraint was assessed using time domain Low Field Nuclear Magnetic Resonance (LFNMR) relaxometry. WRV increased with pretreatment severity, correlating to reduced recalcitrance, as measured by hydrolysis of cellulose using commercial enzyme preparations. Water constraint increased with pretreatment severity, suggesting that a higher level of biomass-water interaction is indicative of reduced recalcitrance in pretreated materials. Both WRV and water constraint increased significantly with reductions in particle size when pretreated materials were further milled, suggesting that particle size plays an important role in biomass water interactions. It is suggested that WRV may be a simple and effective method for measuring and comparing biomass recalcitrance. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:146-153, 2017.

show abstract

The impact of alkali pretreatment and post-pretreatment conditioning on the surface properties of rice straw affecting cellulose accessibility to cellulases

Cited by 49 publications

References 24 publications

Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin

Limitation of cellulose accessibility and unproductive binding of cellulases by pretreated sugarcane bagasse lignin

The productive cellulase binding capacity of cellulosic substrates

Biomass‐water interactions correlate to recalcitrance and are intensified by pretreatment: An investigation of water constraint and retention in pretreated spruce using low field NMR and water retention value techniques

Contact Info

Product

Resources

About