Recycling of cellulases in lignocellulosic hydrolysates using alkaline elution

Rodrigues, Ana Cristina; Leitão, Alexandre F.; Moreira, Susana Margarida Gomes; Felby, Claus; Gama, Miguel

doi:10.1016/j.biortech.2012.01.140

Cited by 60 publications

(59 citation statements)

References 27 publications

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“…The results showed that the cellulase and β-glucosidase activities in the pH 9 washwater were 2.0-3.5 times higher in the washwater at pH 9 than at pH 5. These results are in accordance with those of other researchers who have shown higher enzyme recovery in alkaline conditions [44,45]. It was noted, however, that recovery at the higher pH still only accounted for ≤ 10% of the original FPA enzyme activity.…”

Section: Resultssupporting

confidence: 93%

Improving the performance of enzymes in hydrolysis of high solids paper pulp derived from MSW

Puri

Heaven

Banks

2013

Biotechnol Biofuels

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BackgroundThe research aimed to improve the overall conversion efficiency of the CTec® family of enzymes by identifying factors that lead to inhibition and seeking methods to overcome these through process modification and manipulation. The starting material was pulp derived from municipal solid waste and processed in an industrial-scale washing plant.ResultsAnalysis of the pulp by acid hydrolysis showed a ratio of 55 : 12 : 6 : 24 : 3 of glucan : xylan : araban/galactan/mannan : lignin : ash. At high total solids content (>18.5% TS) single-stage enzyme hydrolysis gave a maximum glucan conversion of 68%. It was found that two-stage hydrolysis could give higher conversion if sugar inhibition was removed by an intermediate fermentation step between hydrolysis stages. This, however, was not as effective as direct removal of the sugar products, including xylose, by washing of the residual pulp at pH 5. This improved the water availability and allowed reactivation of the pulp-bound enzymes. Inhibition of enzyme activity could further be alleviated by replenishment of β-glucosidase which was shown to be removed during the wash step.ConclusionsThe two-stage hydrolysis process developed could give an overall glucan conversion of 88%, with an average glucose concentration close to 8% in 4 days, thus providing an ideal starting point for ethanol fermentation with a likely yield of 4 wt%. This is a significant improvement over a single-step process. This hydrolysis configuration also provides the potential to recover the sugars associated with residual solids which are diluted when washing hydrolysed pulp.

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Section: Resultssupporting

confidence: 93%

Improving the performance of enzymes in hydrolysis of high solids paper pulp derived from MSW

Puri

Heaven

Banks

2013

Biotechnol Biofuels

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“…To overcome these challenges and improve the economic viability of enzymatic hydrolysis, different strategies have been applied: Screening of microorganisms for new lignocellulose-degrading enzymes with better performance (Marjamaa et al, 2013), protein engineering (Thongekkaew et al, 2013), improvement of pretreatment technologies to increase cellulose accessibility (Agbor et al, 2011) or recovery and reuse of cellulases to reduce enzyme cost (Rodrigues et al, 2012). One promising approach to increase the enzymatic hydrolysis of cellulose is the supplementation of surfactants (e.g.…”

Section: Introductionmentioning

confidence: 99%

Dissecting the effect of chemical additives on the enzymatic hydrolysis of pretreated wheat straw

Monschein

Reisinger

Nidetzky

2014

Bioresource Technology

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“…Commercial enzyme cocktails from Novozyme: Celluclast 1.5 L and Novozyme 188 have been widely used as sources of endo- and exoglucanases, and β -glucosidase, respectively, for enzymatic hydrolysis (Arantes & Saddler, 2011; Hu et al, 2013; Kristensen et al, 2007; Qi et al, 2011; Rodrigues et al, 2012; Shi et al, 2011; Zheng et al, 2009) and enzyme recycling by adsorption research (Lu et al, 2002; Qi et al, 2011; Steele et al, 2005; Tu & Saddler, 2010; Tu, Chandra & Saddler, 2007a; Tu, Chandra & Saddler, 2007b). Endo- and exoglucanases present in solution after hydrolysis can be recycled by adsorption onto fresh substrate to start a new round of hydrolysis (Qi et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Stability of commercial glucanase andβ-glucosidase preparations under hydrolysis conditions

Rosales-Calderon

Trajano

Duff

2014

PeerJ

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The cost of enzymes makes enzymatic hydrolysis one of the most expensive steps in the production of lignocellulosic ethanol. Diverse studies have used commercial enzyme cocktails assuming that change in total protein concentration during hydrolysis was solely due to adsorption of endo- and exoglucanases onto the substrate. Given the sensitivity of enzymes and proteins to media conditions this assumption was tested by evaluating and modeling the protein concentration of commercial cocktails at hydrolysis conditions. In the absence of solid substrate, the total protein concentration of a mixture of Celluclast 1.5 L and Novozyme 188 decreased by as much as 45% at 50 °C after 4 days. The individual cocktails as well as a mixture of both were stable at 20 °C. At 50 °C, the protein concentration of Celluclast 1.5 was relatively constant but Novozyme 188 decreased by as much as 77%. It was hypothesized that Novozyme 188 proteins suffer a structural change at 50 °C which leads to protein aggregation and precipitation. Lyophilized β-glucosidase (P-β-glucosidase) at 50 °C exhibited an aggregation rate which was successfully modeled using first order kinetics (R2 = 0.97). By incorporating the possible presence of chaperone proteins in Novozyme 188, the protein aggregation observed for this cocktail was successfully modeled (R2 = 0.96). To accurately model the increasing protein stability observed at high cocktail loadings, the model was modified to include the presence of additives in the cocktail (R2 = 0.98). By combining the measurement of total protein concentration with the proposed Novozyme 188 protein aggregation model, the endo- and exoglucanases concentration in the solid and liquid phases during hydrolysis can be more accurately determined. This methodology can be applied to various systems leading to optimization of enzyme loading by minimizing the excess of endo- and exoglucanases. In addition, the monitoring of endo- and exoglucanases concentrations can be used to build mass balances of enzyme recycling processes and to techno-economically evaluate the viability of enzyme recycling.

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Recycling of cellulases in lignocellulosic hydrolysates using alkaline elution

Cited by 60 publications

References 27 publications

Improving the performance of enzymes in hydrolysis of high solids paper pulp derived from MSW

Improving the performance of enzymes in hydrolysis of high solids paper pulp derived from MSW

Dissecting the effect of chemical additives on the enzymatic hydrolysis of pretreated wheat straw

Stability of commercial glucanase andβ-glucosidase preparations under hydrolysis conditions

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