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Conventional microcrystalline cellulose (MCC) production via aqueous mineral acid hydrolysis is energy- and water-intensive, generating high wastewater volumes. An alternative green chemistry approach employs concentrated gaseous acids to enhance yield and conserve resources. This work aimed to develop an efficient, sustainable gas-phase hydrochloric acid (HCl)-air hydrolysis process for MCC production from cotton linters. MCC yield, structure, powder properties, tablet performance, and environmental impacts were characterized. The gas phase method successfully produced 96% MCC yield and 87% crystallinity, higher than commercial MCC (93% yield, 39% crystallinity). MCC powder exhibited 141 μm mean diameter, 0.91 m2/g surface area, and 245 °C onset decomposition. Tablet testing revealed balanced ductility and toughness. Reduced water (40 kg/kg cellulose), energy (188 MJ/kg MCC), and wastewater generation (39 kg/kg cellulose) were achieved versus conventional production. Tablet testing of MCC compacts revealed balanced ductility and toughness during compression. The HCl-air approach enabled high-yield, high-purity MCC synthesis under mild conditions while enhancing powder attributes, tablet performance, and sustainability compared to commercial manufacturing. [ABSTRACT FROM AUTHOR]

This correction notice is for an article titled "Sustainable Production of Microcrystalline Cellulose Through Gas Phase Hydrolysis for Pharmaceutical Applications: Characterization and Life Cycle Assessment" published in the Journal of Polymers & the Environment. The correction addresses the incorrect affiliation details for authors Fubao Sun and Zahra Echresh Zadeh, which have been swapped. The correct affiliations are provided in the notice. Additionally, there was an error in Figure 6, where the circles marked with letters had a white background, which has been corrected in the updated figure. The publisher, Springer Nature, remains neutral regarding jurisdictional claims and institutional affiliations. [Extracted from the article]

Inhibition of cellulose hydrolysis has been reported extensively, however, there is a paucity of information describing the effect of lignin on xylan hydrolysis by endo-xylanase and β-xylosidase. In this report, the effects of two different lignins on enzymatic hydrolysis of isolated xylan and NaOH-pretreated pennisetum by endo-xylanase and β-xylosidase were assessed. Both acid insoluble lignin (AIL) and enzymatic hydrolysis lignin (EHL) were found to inhibit hydrolysis of endo-xylanase and β-xylosidase, and AIL had a stronger negative effect on enzymatic hydrolysis when compared with that of EHL. Results from inhibitory kinetics experiments showed that the inhibition of AIL and EHL on xylanase did not follow Michaelis–Menten kinetics. The higher adsorption capacity of AIL toward xylanase arose from its higher hydrophobicity and lower absolute zeta potential, and this likely explains the higher inhibitory effect of AIL than that of EHL. The results aid our understanding of the role of lignin in xylan hydrolysis by xylanolytic enzymes. [ABSTRACT FROM AUTHOR]

Correction for 'Non-catalytic proteins as promising detoxifiers in lignocellulosic biomass pretreatment: unveiling the mechanism for enhanced enzymatic hydrolysis' by Meysam Madadi et al., Green Chem., 2023, https://doi.org/10.1039/d3gc01718d. [ABSTRACT FROM AUTHOR]

Abstract: BACKGROUND: The cost of using cellulase to effectively release fermentable sugars from lignocellulosic substrates is still a major impediment to development of the enzyme‐based ‘biorefinery’ industry. This study attempted to optimize a cellulase preparation from on‐site fermentation to efficiently hydrolyse atmospheric glycerol organosolv (AGO)‐pretreated wheat straw. RESULTS: Addition of Cu2+, PEG10000, L‐ascorbic acid and trehalose in the fermentation medium significantly improved the cellulase production. Use of all the additives enabled enhancement to 45.5% of filter paper cellulase (FPA), 14.7% of β‐glucosidase (BG) and 32.4% of carboxymethyl cellulase (CMCase). With the on‐site production of crude cellulase, accessory enzymes (β‐glucosidase (BG), xylanase and lysozyme) and additives (tea saponin (TS) and cationic polyacrylamide (c‐PAM)) were found to facilitate the hydrolysis of AGO‐pretreated substrates effectively. The optimized cellulase mixture allowed 96% of enzymatic hydrolysis at 5 FPU g‐1 for 48 h on addition of 11.5 U g‐1 BG, 180 U g‐1 xylanase, 45 U g‐1 lysozyme, 10 mg g‐1 TS and 2 mg g‐1 C‐PAM, which was twice that of the crude cellulase broth. CONCLUSION: Cellulase customization for specific substrate hydrolysis with on‐site produced broth produced an efficient pathway to lower the enzyme cost in the ongoing lignocellulosic biorefining industry. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The deficiency of family 5 endoglucanase ( Cel5A) and family 6 cellobiohydrolase ( Cel6A) has become a key limiting factor on cellulase enzymatic hydrolysis in bioprocessing of cellulosic biomass. To improve the production of Trichoderma reesei Cel5A / Cel6A, a Vitreoscilla hemoglobin (VHb) gene was tried to co-express extracellularly for the first time with Cel5A / Cel6A in Pichia pastoris GS115. RESULTS Newly constructed recombinant of co-expressing Cel5A / Cel6A extracellularly with VHb was consistent with the single expression at some key variables of culture condition, i.e. inoculum size, initial pH, culture temperature and methanol concentration. Comparing their single expression, the CMCase activity of co-expressed Cel5A and Cel6A enzymes enhanced by 40% and 30%, respectively. With high-cell-density fed-batch (HCDFB) fermentation, the co-expressed Cel5A enzyme activity was 366.8 U mL-1 with 4.3 g L-1 protein content and the Cel6A enzyme activity reached 1.3 U mL-1 with 2.23 g L-1 protein content. The two co-expressed enzyme activities were enhanced by 35% and 20%, respectively, compared with the single expression. CONCLUSION VHb protein capable of binding oxygen can be successfully co-expressed extracellularly with other target proteins. The co-expression of VHb with recombinant Cel5A / Cel6A is efficient at improving oxygen-limited condition and thus enzyme production in both shake-flask and HCDFB fermentation. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

High solid loading enzymatic hydrolysis (HSLEH) produces high sugar concentrations with low water and energy inputs. Adequate information has been provided to confirm the excellent enzymatic digestibility of pretreated bamboo biomass with the solid content below 10%. However, the utilization of bamboo biomass for producing high-concentration sugars solution via HSLEH is rarely reported. In this work, hydrogen peroxide/acetic acid (HPAC) pretreatment removed 79% of lignin from bamboo and HPAC-pretreated bamboo was rich in glucan (55.3%) and xylan (20.4%). In the HSLEH of HPAC-pretreated bamboo, xylanase could increase glucose production by 9.4%. Alkaline incubation could increase the glucose production of HPAC-pretreated bamboo by 6.3% and saved 75% cellulase. The addition of Tween 80 (0.03 g/L) could further increase the glucose production of HPAC-pretreated bamboo by 14.1%. As a result, 204.9 g/L glucose and 60.2 g/L xylose, corresponding to glucose and xylose yields of 75.8% and 65.4% respectively, were obtained from the resulting bamboo solid via 400 g/L HSLEH with 10 FPU cellulase/g dry matter and 0.03 g/L Tween 80, which was the highest concentration compared with the previous literatures. This work developed an integrated process to produce very high-concentration sugars solution from bamboo residue via HSLEH. [Display omitted] • Bamboo biomass provided sugars solution with very high concentration. • High solid loading enzymatic hydrolysis (HSLEH, 400 g/L) of bamboo was performed. • Highest sugars concentration included 204.9 g/L of glucose and 60.2 g/L of xylose. • Input of cellulase (10 FPU/g DM) was minimized during HSLEH of bamboo biomass. [ABSTRACT FROM AUTHOR]

The potential of cellulase enzymes in the developing and ongoing “biorefinery” industry has provided a great motivation to develop an efficient cellulase mixture. Recent work has shown how important the role that the so-called accessory enzymes can play in an effective enzymatic hydrolysis. In this study, three newest Novozymes Cellic CTec cellulase preparations (CTec 1/2/3) were compared to hydrolyze steam pretreated lignocellulosic substrates and model substances at an identical FPA loading. These cellulase preparations were found to display significantly different hydrolytic performances irrelevant with the FPA. And this difference was even observed on the filter paper itself when the FPA based assay was revisited. The analysis of specific enzyme activity in cellulase preparations demonstrated that different accessory enzymes were mainly responsible for the discrepancy of enzymatic hydrolysis between diversified substrates and various cellulases. Such the active role of accessory enzymes present in cellulase preparations was finally verified by supplementation with β-glucosidase, xylanase and lytic polysaccharide monooxygenases AA9. This paper provides new insights into the role of accessory enzymes, which can further provide a useful reference for the rational customization of cellulase cocktails in order to realize an efficient conversion of natural lignocellulosic substrates. [ABSTRACT FROM AUTHOR]

Considering the practical technology–economy of glycerol processing from oleochemicals industry, the ensuing work was proposed to further explore the atmospheric aqueous glycerol autocatalytic organosolv pretreatment (AAGAOP) to improve the enzymatic hydrolysis of lignocellulosic biomass. With the liquid–solid ratio of 20gg−1 at 220°C for 3h, the AAGAOP enabled wheat straw to remove ∼70% hemicelluloses and ∼65% lignin, with ∼98% cellulose retention. The pretreated fiber was achieved with ∼90% of the enzymatic hydrolysis yield after 48h. At oven-drying, dehydration was likely to cause the hornification of fiber, which was responsible for the low enzymatic hydrolysis of dried fiber. With SEM observations, the AAGAOP disrupted wheat straw into thin and fine fibrils, with a small average size and more surface area. The AAGAOP technique, as a novel strategy, enhanced the enzymatic hydrolysis of lignocellulosic biomass by removing the chemically compositional barrier and altering the physically structural impediment. [Copyright &y& Elsevier]

In order to defray the cost of biodiesel production, the ensuing work was to further investigate utilization of the crude glycerol (CG) from oleochemicals industry in the atmospheric autocatalytic organosolv pretreatment (AAOP) to enhance enzymatic hydrolysis. The AAOP–CG enabled wheat straw to achieve with reasonable enzymatic hydrolysis yields, reaching ⩾75% for the wet substrate and ⩽63% for the dried. Lipophilic compounds from the CG formed pitch deposition on the fiber, which was responsible for low delignification (⩽30%) and also troublesome in practical operation. Pitch deposits itself had no significant role on enzymatic hydrolysis. A striking finding of the lignin recondensation and/or lignin–carbohydrate complex helped explain why dried pretreated wheat straw had a low enzymatic hydrolysis yield. The CG was suitable for the AAOP to enhance enzymatic hydrolysis of lignocellulosic biomass. But it was advisable to remove lipophilic compounds from crude glycerol before utilization. [Copyright &y& Elsevier]

• Raw material selected reduces the difficulty of removing aromatic amino acids. • The preparation process improves controllability, repeatability, and can be scaled-up. • High Fischer's ratio corn oligopeptides improve medical value of raw material. • Efficacy of liver injury repair of high Fischer's ratio corn oligopeptides is superior. • High Fischer's ratio corn oligopeptides can prevent early liver injury. Directed hydrolysis of corn crude peptides was performed by sequential digestion with α-chymotrypsin and carboxypeptidase A. With the additional step of adsorption of aromatic amino acids by activated carbon, corn oligopeptides with a Fischer's ratio of 41.87 and low bitterness were prepared. The fraction with molecular weight of 180–1000 Da was found to constitute 71.37% of these oligopeptides, where the proportion of Phe and Tyr among all amino acid residues was only 0.73%. In addition, a model of liver injury induced by carbon tetrachloride was established. Through the analysis of the body–mass index, liver index, liver histopathological features, and various serum biochemical indicators of liver function, high Fischer's ratio corn oligopeptides were found to be safe and slightly superior in terms of liver injury repair when compared with a commercial high Fischer's ratio amino acid product. Crude corn peptides (raw material) and skimmed milk powder had no effect on repairing liver injury. [ABSTRACT FROM AUTHOR]

Acid/base conjugate of acetic acid/sodium acetate solution (AC/SA) can efficiently produce xylooligosaccharides (XOS) with relatively high purity from poplar. The lignin in poplar is an important factor limiting the hydrolysis of xylan using enzymes and dilute acids. Until now, the effect of lignin content of poplar on XOS production by AC/SA hydrolysis is not clear. This work examined the relationship between lignin removal and XOS production from poplar by AC/SA hydrolysis. It was revealed that lignin removal of poplar enhanced XOS yield almost linearly (R2 = 0.95) in AC/SA hydrolysis. Under the optimal conditions (0.15 M AC/SA at a molar ratio of 3.0, 170 °C, 60 min), the highest XOS yield of 55.7% with a low xylose yield of 4.1% was obtained from poplar at a preferential lignin removal of 84.0%. Compared to the optimal XOS production from raw poplar, the XOS yield was increased by 32.3% and xylose production was decreased by 41.4%. Cellulase hydrolysis of the poplar residue produced a satisfying glucose yield of 92.8% and a xylose yield of 88.4%. This work proved that preferential delignification of poplar was vital in XOS and monosaccharides production by AC/SA hydrolysis combined with enzymatic hydrolysis. [Display omitted] • Lignin removal and XOS yield obtained by AC/SA hydrolysis was positively related. • The highest XOS yield of 55.7% was obtained from poplar with 84.0% lignin removal. • By-product of xylose was reduced by 41.4% when poplar was delignified by 84.0%. • Both delignification and AC/SA hydrolysis improved the hydrolyzability of poplar. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mixture of formic, acetic and propionic acids was applied in XOS production. • 60% of propionic acid could be replaced by less expensive formic and acetic acids. • High XOS yield of 69.1% was obtained from corncob by ternary acid mixture. • Hydrolysis temperature could be decreased in ternary acid mixture hydrolysis. Propionic acid (PA) hydrolysis of corncob for xylooligosaccharides (XOS) production has the advantages of simple operation, high XOS yield and less by-products, but the high price of PA limits its application. Therefore, partially replacing PA with less expensive organic acids, such as formic acid (FA) and acetic acid (AC), may lower the cost of hydrolysis in XOS production. This work investigated the feasibility of XOS production from corncob using a tri-acid mixture of FA, AC and PA. A high XOS yield of 69.1 % was achieved under the optimal FA:PA:AC volume ratio of 1:5:4 at 150 °C for 50 min. Overall, in the XOS production from corncob, it was able to replace 60 % of PA with FA and AC, and decreased the hydrolysis temperature from 170 °C to 150 °C, all of which were important to lower the cost of XOS production using organic acid hydrolysis. [ABSTRACT FROM AUTHOR]

Enzymatic hydrolysis is a critical process for the cellulase-mediated lignocellulosic biorefinery to produce sugar syrups that can be converted into a whole range of biofuels and biochemicals. Such a process operating at high-solid loadings (i.e., scarcely any free water or roughly ≥ 15% solids, w/w) is considered more economically feasible, as it can generate a high sugar concentration at low operation and capital costs. However, this approach remains restricted and incurs "high-solid effects", ultimately causing the lower hydrolysis yields with increasing solid loadings. The lack of available water leads to a highly viscous system with impaired mixing that exhibits strong transfer resistance and reaction limitation imposed on enzyme action. Evidently, high-solid enzymatic hydrolysis involves multi-scale mass transfer and multi-phase enzyme reaction, and thus requires a synergistic perspective of transfer and biotransformation to assess the interactions among water, biomass components, and cellulase enzymes. Porous particle characteristics of biomass and its interface properties determine the water form and distribution state surrounding the particles, which are summarized in this review aiming to identify the water-driven multi-scale/multi-phase bioprocesses. Further aided by the cognition of rheological behavior of biomass slurry, solute transfer theories, and enzyme kinetics, the coupling effects of flow-transfer-reaction are revealed under high-solid conditions. Based on the above basic features, this review lucidly explains the causes of high-solid hydrolysis hindrances, highlights the mismatched issues between transfer and reaction, and more importantly, presents the advanced strategies for transfer and reaction enhancements from the viewpoint of process optimization, reactor design, as well as enzyme/auxiliary additive customization. • High-solid enzyme hydrolysis includes multi-scale transfer and multi-phase reaction. • Porous particle properties determine water distribution and enzyme/solute transfer. • Particle rheological behavior link enzyme reaction with transfer. • Deficient water availability is a key limitation to enzyme action in viscous system. • Cellulase customization with auxiliary enzyme/additive benefits the mass transfer. [ABSTRACT FROM AUTHOR]

Fermentable sugar production from lignocellulosic biomass has received considerable attention and has been dramatic progress recently. However, due to low enzymatic hydrolysis (EH) yields and rates, a high dosage of the costly enzyme is required, which is a bottleneck for commercial applications. Over the last decades, various strategies have been developed to reduce cellulase enzyme costs. The progress of the non-catalytic additive proteins in mitigating inhibition in EH is discussed in detail in this review. The low efficiency of EH is mostly due to soluble lignin compounds, insoluble lignin, and harsh thermal and mechanical conditions of the EH process. Adding non-catalytic proteins into the EH is considered a simple and efficient approach to boost hydrolysis yield. This review discussed the multiple mechanical steps involved in the EH process. The effect of physicochemical properties of modified lignin on EH and its interaction with cellulase and cellulose are identified and discussed, which include hydrogen bonding, hydrophobic, electrostatic, and cation- π interactions, as well as physical barriers. Moreover, the effects of different conditions of EH that lead to cellulase deactivation by thermal and mechanical mechanisms are also explained. Finally, recent advances in the development, potential mechanisms, and economic feasibility of non-catalytic proteins on EH are evaluated and perspectives are presented. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Surfactant in glycerol pretreatment facilitated the enzymatic hydrolysis of biomass. • PEG 4000 in pretreatment saved 18.8% energy input with a similar glucose yield. • Coupling surfactants in pretreatment and enzymolysis reduced enzyme usage by 63% • The proposed strategy afforded 1.4 MJ/kg of net energy gain for ethanol production. This study investigated an innovative strategy of incorporating surfactants into alkaline-catalyzed glycerol pretreatment and enzymatic hydrolysis to improve lignocellulosic biomass (LCB) conversion efficiency. Results revealed that adding 40 mg/g PEG 4000 to the pretreatment at 195 °C obtained the highest glucose yield (84.6%). This yield was comparable to that achieved without surfactants at a higher temperature (240 °C), indicating a reduction of 18.8% in the required heat input. Subsequently, Triton X-100 addition during enzymatic hydrolysis of PEG 4000-assisted pretreated substrate increased glucose yields to 92.1% at 6 FPU/g enzyme loading. High-solid fed-batch semi-simultaneous saccharification and co-fermentation using this dual surfactant strategy gave 56.4 g/L ethanol and a positive net energy gain of 1.4 MJ/kg. Significantly, dual assistance with surfactants rendered 56.3% enzyme cost savings compared to controls without surfactants. Therefore, the proposed surfactant dual-assisted promising approach opens the gateway to economically viable enzyme-mediated LCB biorefinery. [ABSTRACT FROM AUTHOR]

[Display omitted] • PEG grafting onto lignin preserved β-O-4 linkages, reduced phenolic OH groups. • PEG 4000 addition increased glucose yield by 35% in glycerol organosolv pretreatment. • PEG reduced lignin hydrophobicity and non-productive enzyme adsorption. • Simulations showed PEG-lignin interactions prevented repolymerization. • Modified lignin structure enhanced enzymatic hydrolysis, enabling biorefinery applications. Organosolv pretreatment effectively fractionates lignocellulosic biomass for efficient enzymatic hydrolysis, yielding fermentable sugars. However, substantial lignin redeposition on the substrate surface and residual lignin content exacerbate lignin's inhibitory effects on subsequent enzymatic hydrolysis. An in-situ lignin modification is proposed to address this challenge by incorporating polyethylene glycol (PEG) series into glycerol organosolv (GO) pretreatment. According to the results obtained, PEG-assisted GO pretreated substrate exhibited significantly increased sugar yield during enzymatic hydrolysis, particularly with PEG 4000, showing 35.4% higher glucose yield over 72 h. The improved glucose yield with PEG could be attributed to changes in the physicochemical structure and properties of residual lignin, mitigating its non-productive interaction with cellulase enzymes. PEG's presence in GO pretreatment also increased β-O-4 linkages preservation by 55% and reduced phenolic hydroxyl groups by 28% in lignin fragments versus no surfactants. This outcome resulted from introducing glycerol and PEG hydroxyl tails into the lignin structure, forming α-etherified lignin and rendering it more hydrophilic. Simulations confirmed strong Van Der Waals and hydrogen bonding interactions between lignin units and PEG, hindering lignin fragments repolymerization. Incorporating PEG in the organosolv pretreatment proves highly beneficial for cellulase-mediated lignocellulosic biorefinery, resembling a lignin-first strategy. The optimized process enables efficient biomass utilization for sustainable fuels and chemicals production. [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]

• β-Cyclodextrin and PVC were co-carbonised and sulfonated for catalyst synthesis. • Mixed carbon carrier increased –SO 3 H density with bearing –Cl binding domain. • Catalysts directionally promoted disaccharide hydrolysis with strong bond fracture. • Binding domains played important role in decreasing activation energy. • Monosaccharide generation achieved relatively low activation energy of 98.6 kJ/mol. A multifunctional carbon solid acid with binding and catalytic domains was prepared by co-carbonisation of β-cyclodextrin and polyvinyl chloride followed by sulfonation. The abundant –OH group on the surface of β-cyclodextrin cavity increased the hydrophilicity and dispersibility of catalyst, and the grafting of –Cl group collectively promoted its adsorption performance (45.8% within 6 h). Additionally, the oxidation and substitution of alkyl chains and aliphatic bridges in carbon precursors were responsible to introduce catalytic functional –SO 3 H group. The catalyst directionally facilitated disaccharide hydrolysis with strong bond-breaking effects on α–1, 4 and β–1, 4–glycosidic bonds; the hydrolysis rates ranged 72.7%–84.3%, and the monosaccharide yields ranged 68.7%–78.2%. However, the destruction of α–1, 1–glycosidic bond was weak, and the fracture of α, β–1, 2–glycosidic bond was likely to cause fructose decomposition. The reaction rate constants of glucose production and decomposition increased with the increase of temperature. The apparent activation energy of glucose production was 98.6 kJ/mol, decreased by 25.9% and 10.4% compared with homogeneous dilute acids and conventional carbon solid acids. The binding domains of catalyst not only played important role in enhancing the surface hydrolysis reaction of saccharides, but also decreased the activation energies. [ABSTRACT FROM AUTHOR]