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Due to the poor enzyme thermal stability, the efficient conversion of high crystallinity cellulose into glucose in aqueous phase over 50 °C is challenging. Herein, an enzyme‐induced MOFs encapsulation of β‐glucosidase (β‐G) strategy was proposed for the first time. By using various methods, including SEM, XRD, XPS, NMR, FTIR and BET, the successful preparation of a porous channel‐type flower‐like enzyme complex (β‐G@MOFs) was confirmed. The prepared enzyme complex (β‐G@MOFs) materials showed improved thermal stability (from 50 °C to 100 °C in the aqueous phase) and excellent resistance to ionic liquids (the reaction temperature was as high as 110 °C) compared to the free enzyme (β‐G). Not only the catalytic hydrolysis of cellulose by single enzyme (β‐G) in ionic liquid was realized, but also the high‐temperature continuous reaction performance of the enzyme was significantly improved. Benefiting from the significantly improved heat resistance, the β‐G@MOFs exhibited 32.1 times and 34.2 times higher enzymatic hydrolysis rate compared to β‐G for cellobiose and cellulose substrates, respectively. Besides, the catalytic activity of β‐G@MOFs was retained up to 86 % after five cycles at 110 °C. This was remarkable because the fixation of the enzyme by the MOFs ensured that the folded structure of the enzyme would not expand at high temperatures, allowing the native conformation of the encapsulated protein well‐maintained. Furthermore, we believe that this structural stability was caused by the confinement of flower‐like porous MOFs. [ABSTRACT FROM AUTHOR]

A linear pH-responsive zwitterionic copolymer P(MDB) was synthesized from functional monomers methacrylic acid, 2-(dimethylamino) ethyl methacrylate (DMA) and benzyl methacrylate (BMA) through free radical polymerization to recover cellulases and enhance the enzymatic hydrolysis. The hydrophobicity and molecular weight of the copolymer was controlled by the feed ratio of monomers and the mass ratio of initiator to monomers, respectively. UV-turbidity showed P(MDB) exhibited sensitive pH-responsiveness with dissolution–precipitation ΔpH about 1 pH unit. The precipitation pHφ of P(MDB) was 5.0–5.5 and over 90% of P(MDB) could precipitate in the vicinity of its isoelectric point. Increasing the hydrophobicity or molecular weight of P(MDB) could improve its pH sensitivity and precipitation rate. P(MDB) could enhance the enzymatic hydrolysis of dilute acid pretreated Eucalyptus by 10–25%. P(MDB) could recover the free cellulases in enzymatic hydrolysate by co-precipitation. SDS-PAGE analysis showed that P(MDB) could recover 100% β-glucosidase (β-GL) and the recovery rates of cellobiohydrolase (CBH) and endoglucanase (EG) increased as the hydrophobicity and molecular weight of P(MDB) increased. The mechanism was proposed that hydrophobic affiliation was the main binding force of P(MDB) to cellulases. Increasing the hydrophobicity and molecular weight of copolymer could increase its binding force and the number of binding sites to cellulases thus the overall cellulase recovery performance was improved. [ABSTRACT FROM AUTHOR]

Effect of hydrogen bond breaker (urea) addition on the enzymatic hydrolysis of Avicel and eucalyptus pretreated by dilute acid (Eu-DA) was investigated. Urea enhanced the enzymatic hydrolysis of Eu-DA at 50 or 30 °C when the concentration of urea was below 60 g/L, while it inhibited the hydrolysis of Avicel. Low concentration urea (< 240 g/L) had little effect on the cellulase spatial structure and its activity. But it decreased cellulase binding to cellulose surface to inhibit the cellulose hydrolysis. Meanwhile, urea obviously prevented the adsorption of cellobiohydrolase I (CBHI) on the lignin in spite of little effect on the adsorption of β-glucosidase (BGL) and two endoglucanases (EGIII and EGV) on lignin. It was proposed that urea enhanced the enzymatic efficiency of Eu-DA by decreasing the cellulase adsorption on lignin surface. [ABSTRACT FROM AUTHOR]

Effects of nonionic surfactants on enzymatic hydrolysis of Avicel at different agitation rates and solid loadings and the mechanism were studied. Nonionic surfactants couldn’t improve the enzymatic hydrolysis efficiency at 0 and 100 rpm but could enhance the enzymatic hydrolysis significantly at high agitation rate (200 and 250 rpm). Cellulase was easily deactivated at high agitation rate and the addition of nonionic surfactants can protect against the shear-induced deactivation, especially when the cellulase concentration was low. When 25 mg protein/L of cellulase solution was incubated at 200 rpm for 72 h, the enzyme activity increased from 36.0% to 89.5% by adding PEG4600. Moreover nonionic surfactants can compete with enzyme in air-liquid interface and reduce the amount of enzyme exposed in the air-liquid interface. The mechanism was proposed that nonionic surfactants could enhance the enzymatic hydrolysis of Avicel by reducing the cellulase deactivation caused by shear force and air-liquid interface. [ABSTRACT FROM AUTHOR]

In order to enhance the enzymatic hydrolysis of lignocelluloses and recycle surfactants after enzymatic hydrolysis, a pH-responsive lignin amphoteric surfactant (SLQA) was prepared by the quaternization of sulfonated lignin (SL). Compared with SL, SLQA could much more effectively enhance the enzymatic hydrolysis of lignocelluloses. With an increase in the quaternization degree, enhancement of the enzymatic hydrolysis of lignocelluloses by the SLQA gradually increased. Adding 2 g L−1 SLQA-80 (mass radio of quaternizing agent to SL was 80%) could increase the enzymatic digestibility of pretreated eucalyptus and corncob residues (CCR) from 36.7% and 37.8% to 84.3% and 90.5%, respectively. The adsorption of SLQA on lignin film was larger than that of SL, and the lignin film became more hydrophilic after adsorbing SLQA. Thus, SLQA could cause more effective steric hindrance and form a hydration layer to reduce the non-productive adsorption of cellulase on lignin. The purified SLQA-80 exhibited sensitive pH-responsive property, and 90.8% of SLQA-80 could be recycled by adjusting the pH of hydrolysate after enzymatic hydrolysis. Adding recyclable SLQA could not only obviously enhance the enzymatic hydrolysis of lignocelluloses, but could also enable the comprehensive utilization of lignocelluloses. This method is of great significance to reducing the cost of cellulosic ethanol. [ABSTRACT FROM AUTHOR]

Nonionic surfactants could effectively improve the enzymatic hydrolysis efficiency of lignocellulose, while small molecule anionic and cationic surfactants usually inhibited the enzymatic hydrolysis. The results showed that the anionic surfactant sodium dodecyl sulfate (SDS) could improve the enzymatic hydrolysis efficiency of Avicel at the concentration range of 0.1-1 mM, but it did inhibit enzymatic hydrolysis at higher concentration. Cationic surfactant cetyltrimethylammonium bromide (CTAB) was used to regulate the surface charge of SDS; thereby catanionic surfactant SDS-CTAB was formed. The effect of SDS-CTAB catanionic surfactant with varied molar ratios on the enzymatic hydrolysis of pure cellulose and corn stover at various enzymatic hydrolysis environments was investigated. SDS-CTAB could increase the enzymatic hydrolysis of corn stover at high solid loading from 33.3 to 42.4%. Using SDS-CTAB could reduce about 58% of the cellulase dosage to achieve 80% of the enzymatic hydrolysis of corn stover. SDS-CTAB catanionic surfactant could regulate the surface charge of cellulase in the hydrolyzate and reduce the non-productive adsorption of cellulase on the lignin, thereby improving the enzymatic hydrolysis efficiency of lignocellulose. [ABSTRACT FROM AUTHOR]

Effect of cationic surfactants alkyltrimethylammonium bromide (CTAB) with varied alkyl chain lengths on the enzymatic hydrolysis of Avicel and the surface charge of cellulase was investigated. Enzymatic hydrolysis of Avicel increased linearly from 42.1 to 61.4 % with the increase of the concentration of cetyltrimethylammonium bromide (CTAB) logarithmically from 0.0001 to 0.01 mM, and reached a maximum value at the concentration of 0.01-0.03 mM. When the concentration was increased further, the cellulase solution became positively charged and the enzymatic hydrolysis of Avicel decreased rapidly. With the increasing alkyl chain length, CTAB provided more proton and neutralized the negative charge of cellulase more obviously. Therefore, the required concentration of CTAB could be less to enhance the enzymatic hydrolysis of Avicel. In addition, CTAB could enhance enzymatic hydrolysis efficiency of corncob at high solid content from 35.0 to 56.3 %; CTAB could reduce about 60 % of the cellulase loading in the enzymatic hydrolysis of corncob to obtain the same glucose yield. Effect of CTAB on the enzymatic hydrolysis of typical pretreated softwood and hardwood was also investigated. This study laid the foundation for using CTAB to recover cellulase, and provided the design direction for cellulase with higher activity and better stability by adjusting its hydrophilicity and chargeability. [ABSTRACT FROM AUTHOR]

A novel pretreatment process using NaOH/Urea solution at room temperature was developed to overcome recalcitrance of lignocellulose for efficient bioconversion of miscanthus. The process consists of mechanical size reduction, pretreatment with NaOH/Urea solution, and filtration. The results indicated that the substrate enzymatic digestibility (SED) of miscanthus pretreated with 8 wt% NaOH and 12 wt% urea at 21 C for 30 min was up to 71.99 % at low enzyme loading of 5 filter paper units (FPU)/g glucan after 72 h hydrolysis. NaOH/Urea pretreatment efficiently removed lignin and hemicellulose. And their removal rates increased with the increase of pretreatment temperature, NaOH dosage and urea dosage. With the increase of NaOH dosage, the chemical composition removal rate decreased in the following order: lignin, xylan, araban, galactan. Meanwhile, NaOH/Urea pretreatment could open up the fiber structure, decrease cellulose crystallinity index, and prevent lignin droplets depositing on cellulose. The optimal condition for the NaOH/Urea pretreatment regarding this study was 6 wt% NaOH/12 wt% urea and 21 °C. Approximately 70 % glucose yield was achieved upon this condition. [ABSTRACT FROM AUTHOR]

Sodium lignosulfonate (SXSL) and long-chain fatty alcohols (LFAs) could enhance the enzymatic hydrolysis of xylan, and the compound of SXSL and LFAs have synergies on the enzymatic hydrolysis. SXSL shows a strong enhancement in buffer pH range from 4.0 to 6.0. The enhancement increased with the SXSL dosage and the xylanase loading. The cellulose and lignin in corncob substrate could not only adsorb xylanase nonproductively, but also seriously reduce the accessibility of xylanase on xylan to impede the enzymatic hydrolysis of xylan. Cellulase could break the plant cell wall structure of corncob and make additives work better. The xylose yield of corncob at 72 h increased from 59.4% to 73.7% by adding the compound of 5 g/L SXSL and 0.01% (v/v) n -decanol, which was higher than that without cellulase and additives by 30.7%. Meanwhile, the glucose yield at 72 h of corncob increased from 45.8% to 62.3%. [ABSTRACT FROM AUTHOR]

The effects of long-chain fatty alcohols (LFAs) on the enzymatic hydrolysis of crystalline cellulose by two commercial Trichoderma reesei cellulase cocktails (CTec2 and Celluclast 1.5L) were studied. It was found that n-butanol inhibited the enzymatic hydrolysis, but n-octanol, n-decanol and n-dodecanol had strong enhancement on enzymatic hydrolysis of crystalline cellulose in the buffer pH range from 4.0 to 6.0. LFAs can increase the hydrolysis efficiency of crystalline cellulose from 37 to 57 % at Celluclast 1.5L loading of ten filter paper units (FPU)/g glucan. LFAs have similar enhancement on the enzymatic hydrolysis of crystalline cellulose mixed with lignin or xylan. The enhancement of LFAs increased with the decrease of the crystallinity index. LFAs not only enhanced the high-solid enzymatic hydrolysis of lignocellulose, but also improved the rheological properties of high-solid lignocellulosic slurries by decreasing the yield stress and complex viscosity. Meanwhile, LFAs can improve the enzymatic hydrolysis of cellobiose to glucose, especially at low cellulase loading. [ABSTRACT FROM AUTHOR]

The effects of lignosulfonate (LS) on enzymatic saccharification of pure cellulose were studied. Four fractions of LS with different molecular weight (MW) prepared by ultrafiltration of a commercial LS were applied at different loadings to enzymatic hydrolysis of Whatman paper under different pH. Using LS fractions with low MW and high degree of sulfonation can enhance enzymatic cellulose saccharification despite LS can bind to cellulase nonproductively. The enhancing effect varies with LS properties, its loading, and hydrolysis pH. Inhibitive effect on cellulose saccharification was also observed using LS with large MW and low degree of sulfonation. The concept of 'LS-cellulase aggregate stabilized and enhanced cellulase binding' was proposed to explain the observed enhancement of cellulose saccharification. The concept was demonstrated by the linear correlation between the measured amount of bound cellulase and saccharification efficiency with and without LS of different MW in a range of pH. [ABSTRACT FROM AUTHOR]

Highlights: [•] SL clearly reduced the non-productive adsorption of cellulase on lignin. [•] SL with higher MW had stronger blocking effect on cellulase adsorption on lignin. [•] Linear anionic aromatic polymers strongly blocked cellulase adsorption on lignin. [•] Copolymer of lignin and PEG had stronger enhancement than PEG. [Copyright &y& Elsevier]

This study revealed that cellulose enzymatic saccharification response curves of lignocellulosic substrates were very different from those of pure cellulosic substrates in terms of optimal pH and pH operating window. The maximal enzymatic cellulose saccharification of lignocellulosic substrates occurs at substrate suspension pH 5. 2- 6. 2, not between pH 4. 8 and 5. 0 as exclusively used in literature using T. reesi cellulase. Two commercial cellulase enzyme cocktails, Celluclast 1.5L and CTec2 both from Novozymes, were evaluated over a wide range of pH. The optimal ranges of measured suspension pH of 5.2-5.7 for Celluclast 1.5L and 5.5-6.2 for CTec2 were obtained using six lignocellulosic substrates produced by dilute acid, alkaline, and two sulfite pretreatments to overcome recalcitrance of lignocelluloses (SPORL) pretreatments using both a softwood and a hardwood. Furthermore, cellulose saccharification efficiency of a SPORL-pretreated lodgepole pine substrate showed a very steep increase between pH 4.7 and 5.2. Saccharification efficiency can be increased by 80 % at cellulase loading of 11.3 FPU/g glucan, i.e., from approximately 43 to 78 % simply by increasing the substrate suspension pH from 4.7 to 5.2 (buffer solution pH from 4.8 to 5.5) using Celluclast 1.5L, or by 70 % from approximately 51 to 87 % when substrate suspension pH is increased from 4.9 to 6.2 (buffer solution pH from 5.0 to 6.5) using CTec2. The enzymatic cellulose saccharification response to pH is correlated to the degree of substrate lignin sulfonation. The difference in pH-induced lignin surface charge, and therefore surface hydrophilicity and lignin-cellulase electrostatic interactions, among different substrates with different lignin content and structure is responsible for the reported different enhancements in lignocellulose saccharification at elevated pH. [ABSTRACT FROM AUTHOR]

[Display omitted] • PSSP with UCST response was recyclable. • PSSP could enhance high-solids enzymatic hydrolysis of lignocellulose. • Cellulase was efficiently recovered by co-precipitating with PSSP. • For CCR system, 50% of cellulase amounts was saved with adding PSSP 3. The enzymatic hydrolysis cost of lignocellulose can be reduced by improving enzymatic hydrolysis and recycling cellulase by adding additives. A series of copolymers P(SSS-co-SPE) (PSSPs) were synthesized using sodium p-styrene sulfonate (SSS) and sulfobetaine (SPE) as monomers. PSSP exhibited upper critical solution temperature response. PSSP with high molar ratio of SSS displayed more significant improved hydrolysis performance. When 10.0 g/L PSSP 5 was added to the hydrolysis system of corncob residues, and substrate enzymatic digestibility at 72 h (SED@72 h) increased by 1.4 times. PSSP with high molecular weight and moderate molar ratio of SSS, had significant temperature response, enhanced hydrolysis, and recovering cellulase properties. For high-solids hydrolysis of corncob residues, SED@48 h increased by 1.2 times with adding 4.0 g/L of PSSP 3. Meanwhile, 50% of cellulase amount was saved at the room temperature. This work provides a new idea for reducing the hydrolysis cost of lignocellulose-based sugar platform technology. [ABSTRACT FROM AUTHOR]

Effect of the molecular structure of lignosulfonate-based polyoxyethylene ether (LS-PEG) on the enzymatic hydrolysis of Avicel and corn stover was investigated. With the increase of PEG contents and M w of LS-PEG, glucose yield of corn stover increased from 16.7% to 51.9%. When LS-PEG was compounded with cationic surfactant cetyltrimethylammonium bromide (CTAB), the enhancement of glucose yield of corn stover was further increased from 45.3% to 62.8%. Sulfonic group of LS-PEG preferentially interacted with quaternary ammonium group of CTAB by the electrostatic attraction to form a similar non-ionic surfactant CTAB-LS-PEG. CTAB-LS-PEG showed electrically neutral and more hydrophobic, and blocked more nonproductive adsorption of cellulase on the lignin. Therefore, CTAB-LS-PEG enhanced enzymatic hydrolysis efficiency of lignocelluloses more significantly. The understanding developed in this study can help to develop potential approaches and strategies for effective application of lignosulfonate to improve bioconversion of lignocellulosic biomass. [ABSTRACT FROM AUTHOR]

• Lignin-based surfactants LC and LCQ with various isoelectric points were synthesized. • The effect and mechanism of the pI of LCQ on the enzymatic hydrolysis were studied. • The SED of Eu-SPORL increased from 35.2% to 95.3% by adding LCQ-40. • LCQ could be efficiently recovered for the excellent pH-response performance. The isoelectric point (pI) of lignin-based surfactant is an important factor in the enhancement on the enzymatic hydrolysis of lignocellulose. In this work, lignin carboxylate (LC) and quaternary ammonium lignin carboxylates (LCQ-x, x%: the mass ratio of quaternizing agent to enzymatic hydrolysis lignin) with different isoelectric points were synthesized. LC or LCQ-x with pI significantly lower or higher than 4.8 reduced the non-productive adsorption of cellulase on lignin, but for the significant inhibitory effect on cellulase activity, their enhancements on the enzymatic hydrolysis of lignocellulose were not remarkable. However, LCQ-x with pI around 4.8 preserved the cellulase activity, and significantly reduced the non-productive adsorption of cellulase, therefore remarkably enhanced the enzymatic hydrolysis. 2 g/L LC, LCQ-40 (pI = 5.0) and LCQ-100 (pI = 9.2) increased the enzymatic digestibility of pretreated eucalyptus from 35.2% to 53.4%, 95.3% and 60.4% respectively. In addition, for the excellent pH-response performance, LCQ could be efficiently recovered after enzymatic saccharification. [ABSTRACT FROM AUTHOR]

Hydrolyzing lignocellulose, the most abundant biomass raw material in nature, into monosaccharides by enzymes and then transforming the sugars into chemicals and fuels by biological or chemical methods is one of the most important parts of biorefining. In lignocellulosic biomass, cellulose is often tightly wrapped by lignin along with hemicelluloses. Although some pretreatments can partially remove lignin, residual lignin in pretreated substrates still physically blocks the accessibility of cellulose, non-productively adsorbs cellulases, and sterically hinders the enzymatic hydrolysis of cellulose. So, lignin is generally considered to be an inhibitor to the enzymatic hydrolysis of lignocellulosic substrates. However, new research shows that under the right conditions, lignin does not inhibit the enzymatic hydrolysis of lignocellulose, and can even increase the final sugar yield. For example, recently, some novel lignin-target pretreatments have been developed, they can reduce or overcome the inhibitory effect of lignin. And researchers also find that lignin can be functionalized and used as an activator/promoter of enzymatic hydrolysis of lignocellulose, their effectiveness is comparable to common high-efficiency surfactants. What's more, different lignin-based carriers were also synthesized to carry and recycle cellulases during the hydrolysis, they can obviously reduce the load and cost of cellulases. These works indicate that lignin can play a positive role in the enzymatic hydrolysis of lignocellulose. In order for readers to dialectically view lignin and understand its multiplicity, this review is to report the progress in the studies of how researchers tame the "lignin dog" to facilitate enzymatic hydrolysis of lignocellulose. • Concept of taming "lignin dog" to facilitate enzymatic hydrolysis is proposed. • Pretreatments are classified based on structure changes for in-depth understanding. • Effects of lignin-based additives on enzymatic hydrolysis are systematically introduced. • Lignin-based carriers for cellulase recovery were summarized for the first time. • Lignin-related challenges in enzymatic hydrolysis are prospected with reliable analysis. [ABSTRACT FROM AUTHOR]

Some zwitterionic surfactants exhibit upper critical solution temperature (UCST) in aqueous solutions. For the zwitterionic surfactant solution mixed with cellulase, when its temperature is below UCST, the cellulase can be recovered by coprecipitation with zwitterionic surfactant. In this work, 3-(Hexadecyldimethylammonio) propanesulfonate (SB3-16) was selected to enhance the enzymatic hydrolysis of lignocelluloses and recover the cellulase. After adding 2 mmol/L of SB3-16, the enzymatic digestibility of eucalyptus pretreated by dilute acid (Eu-DA) and by sulfite (Eu-SPORL) increased from 27.9% and 35.1% to 72.6% and 89.7%, respectively. The results showed that SB3-16 could reduce the non-productive adsorption of cellulase on hydrophobic interface, while it did not significantly inhibit the activity of cellulase. For the solution contained 1 wt% SB3-16 and 200 mg protein/L CTec2 cellulase, 55.2% of protein could be recovered by cooling. The filter paper activity of the recovered cellulase was 1.93 FPU/mg protein, which was 95.8% of its initial activity. [ABSTRACT FROM AUTHOR]

Polyvinylpyrrolidone (PVP) is an antifouling polymer to resist the adsorption of protein on solid surface. Effects of PVP on the enzymatic hydrolysis of pretreated lignocelluloses and its mechanism were studied. Adding 1 g/L of PVP8000, the enzymatic digestibility of eucalyptus pretreated by dilute acid (Eu-DA) was increased from 28.9% to 73.4%, which is stronger than the classic additives, such as PEG, Tween and bovine serum albumin. Compared with PEG4600, the adsorption of PVP8000 on lignin was larger, and the adsorption layer was more stable and hydrophilic. Therefore, PVP8000 reduced 73.1% of the cellulase non-productive adsorption on lignin and enhanced the enzymatic hydrolysis of lignocelluloses greatly. [ABSTRACT FROM AUTHOR]

The cost of lignocellulosic enzymatic hydrolysis was reduced by enhancing enzymatic hydrolysis and recycling cellulase. Lignin-grafted quaternary ammonium phosphate (LQAP) with sensitive temperature and pH response, was obtained by grafting quaternary ammonium phosphate (QAP) onto enzymatic hydrolysis lignin (EHL). LQAP dissolved under the hydrolysis condition (pH 5.0, 50 °C) and enhanced the hydrolysis. After hydrolysis, LQAP and cellulase co-precipitated by the hydrophobic binding and electrostatic attraction, when lowering pH to 3.2, and cooling to 25 °C. LQAP had significant performances of pH-UCST response, enzymatic hydrolysis enhancement and cellulase recovery at the same time. When 3.0 g/L LQAP-100 was added to the system of corncob residue, SED@48 h increased from 62.6 % to 84.4 %, and 50 % of amount of cellulase was saved. Precipitation of LQAP at low temperature was mainly attributed to the salt formation of positive and negative ions in QAP; LQAP enhanced the hydrolysis for its ability to decrease the ineffective adsorption of cellulase by forming a hydration film on lignin and through the electrostatic repulsion. In this work, a lignin amphoteric surfactant with temperature response, was used to enhance hydrolysis and recover cellulase. This work will provide a new idea for reducing the cost of lignocellulose-based sugar platform technology, and high-value utilization of industrial lignin. A sensitive pH-UCST-type LQAP was used to significantly enhance lignocellulosic enzymatic hydrolysis and efficiently recycle cellulase, and the process is sustainable while realizing the value-added utilization of industrial lignin. [Display omitted] [ABSTRACT FROM AUTHOR]

Two pretreatment methods to overcome recalcitrance of lignocelluloses, sulfite pretreatment (SPORL) and dilute acid (DA), were conducted to pretreat softwood masson pine and hardwood eucalyptus for enzymatic hydrolysis. In the presence of corresponding pre-hydrolysates, adding moderate cetyltrimethylammonium bromide (CTAB) could enhance the enzymatic hydrolysis of the SPORL-pretreated substrates, but had no enhancement for the DA-pretreated substrates. The results showed that sodium lignosulfonate (SL) in pre-hydrolysates and CTAB together had a strong enhancement on the enzymatic hydrolysis of lignocelluloses. The compound of commercial lignosulfonate SXSL and CTAB (SXSL-CTAB) could enhance the substrate enzymatic digestibility (SED) of SPORL-pretreated masson pine from 27.1% to 71.0%, and that of DA-pretreated eucalyptus from 37.6% to 67.9%. The mechanism that CTAB increased the adsorption of SL on lignin to form more effective steric hindrance and reduced the non-productive adsorption of cellulase on lignin by neutralizing the negative charge of SL was proposed. [ABSTRACT FROM AUTHOR]

Effect of the molecular structure of lignin-based polyoxyethylene ether (EHL–PEG) on enzymatic hydrolysis of Avicel and corn stover was investigated. With the increase of PEG contents and molecular weight of EHL–PEG, glucose yield of corn stover increased. EHL–PEG enhanced enzymatic hydrolysis of corn stover significantly at buffer pH 4.8–5.5. Glucose yield of corn stover at 20% solid content increased from 32.8% to 63.8% by adding EHL–PEG, while that with PEG4600 was 54.2%. Effect of EHL–PEG on enzymatic hydrolysis kinetics of cellulose film was studied by quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). An enhancing mechanism of EHL–PEG on enzymatic hydrolysis kinetics of cellulose was proposed. Cellulase aggregates dispersed by EHL–PEG excavated extensive cavities into the surface of cellulose film, making the film become more loose and exposed. After the maximum enzymatic hydrolysis rate, the film was mainly peeled off layer by layer until equilibrium. [ABSTRACT FROM AUTHOR]

Water-soluble lignin-based polyoxyethylene ether (EHL–PEG), prepared from enzymatic hydrolysis lignin (EHL) and polyethylene glycol (PEG1000), was used to improve enzymatic hydrolysis efficiency of corn stover. The glucose yield of corn stover at 72 h was increased from 16.7% to 70.1% by EHL–PEG, while increase in yield with PEG4600 alone was 52.3%. With the increase of lignin content, EHL–PEG improved enzymatic hydrolysis of microcrystalline cellulose more obvious than PEG4600. EHL–PEG could reduce at least 88% of the adsorption of cellulase on the lignin film measured by quartz crystal microbalance with dissipation monitoring (QCM-D), while reduction with PEG4600 was 43%. Cellulase aggregated at 1220 nm in acetate buffer analyzed by dynamic light scattering. EHL–PEG dispersed cellulase aggregates and formed smaller aggregates with cellulase, thereby, reduced significantly nonproductive adsorption of cellulase on lignin and enhanced enzymatic hydrolysis of lignocelluloses. [ABSTRACT FROM AUTHOR]

• Highly recyclable SC was used in lignocellulosic enzymatic hydrolysis. • Using SC to enhance cellulase recovery through ingenious pH regulation. • SC increased the sugar yield of Eu-DA by 95.5% and save at least 40% cellulase. Most additives that capable of enhancing enzymatic hydrolysis of lignocellulose are petroleum-based, which are not easy to recycle with poor biodegradability. In this work, highly recyclable and biodegradable sodium caseinate (SC) was used to enhance lignocellulosic hydrolysis with improved cellulase recyclability. When the pH decreased from 5.5 to 4.8, more than 96% SC could be precipitated from the solution and recovered. Adding SC increased enzymatic digestibility of dilute acid pretreated eucalyptus (Eu-DA) from 39.5% to 78.2% under Eu-DA loading of 10 wt% and pH = 5.5, and increase cellulase content in 72 h hydrolysate from only 15.2% of the original to 60.0%, which facilitated the recovery of cellulases through re-adsorption by fresh substrates. With multiple cycles of re-adsorption, application of SC not only increased the sugar yield of Eu-DA by 95.5%, but also reduced cellulase loading by 40%. [ABSTRACT FROM AUTHOR]