pH profiles of cellulases depend on the substrate and architecture of the binding region

Røjel, Nanna Sandager; Kari, Jeppe; Sørensen, Trine Holst; Borch, Kim

doi:10.1002/bit.27206

Cited by 7 publications

(6 citation statements)

References 51 publications

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“…Enzyme engineering strategies include directed evolution, usually based on combining random and sitedirected mutagenesis steps [124,244,368], modification of the linker region of bimodular cellulases [14,313] and domain shuffling, i.e., creation of fusion/chimeric proteins by combining (partial or complete sequences of) catalytic domains and CBMs from different enzymes/organisms [138,331,337,369]. Despite the tremendous work that has been done for cellulase optimization, we are still trying to understand certain fundamentals of how EGs and CBHs work, and work together, the aim being to develop better (mixtures of) EGs and CBHs [176,203,257,303,362].…”

Section: Today's Cellulase Cocktails: What Are the Limitations And Homentioning

confidence: 99%

Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives

Østby

Hansen

Horn

et al. 2020

Journal of Industrial Microbiology and Biotechnology

129

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Efficient saccharification of lignocellulosic biomass requires concerted development of a pretreatment method, an enzyme cocktail and an enzymatic process, all of which are adapted to the feedstock. Recent years have shown great progress in most aspects of the overall process. In particular, increased insights into the contributions of a wide variety of cellulolytic and hemicellulolytic enzymes have improved the enzymatic processing step and brought down costs. Here, we review major pretreatment technologies and different enzyme process setups and present an in-depth discussion of the various enzyme types that are currently in use. We pay ample attention to the role of the recently discovered lytic polysaccharide monooxygenases (LPMOs), which have led to renewed interest in the role of redox enzyme systems in lignocellulose processing. Better understanding of the interplay between the various enzyme types, as they may occur in a commercial enzyme cocktail, is likely key to further process improvements.

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Section: Today's Cellulase Cocktails: What Are the Limitations And Homentioning

confidence: 99%

Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives

Østby

Hansen

Horn

et al. 2020

Journal of Industrial Microbiology and Biotechnology

129

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“…The cellulose hydrolyses were performed at varied temperatures between 25 and 75 • C, pH values between 3.5 to 8.0, and incubation times of 21 days. On a practical level of understanding the effect of environmental parameters on enzymatic activity, previous studies have called for the caution of the common practices of using soluble substrates [63], like the CMC-a carboxylated derivative of cellulose as the here used cellulose nanofibers-for the general characterization of pH and temperature effects on cellulase activity. For the CMC degradation studies in solution (homogeneous conditions), 20 mg of cellulase-encapsulated alginate particles were added to 900 µL of a 1% (w/v) solution of CMC in acetate buffer at a given pH.…”

Section: Cellulose Enzymatic Degradation-cellulase Activity Assaymentioning

confidence: 99%

“…In comparison to free enzyme, the immobilization enabled extending the spectrum of effective utilization of the enzyme at higher temperatures ( Figure 2, and Figure S2 in Supporting Material), indicating that the immobilization improves the thermal stability of the enzyme. The cellulases from Trichoderma reesei present carbohydrate binding moieties which might favor interaction of the enzyme with the alginate matrix [63]. It should contribute to slightly shift the temperature of maximum enzyme stability to higher values when being entrapped in the alginate matrix.…”

Section: Thermogravimetric Analysismentioning

confidence: 99%

“…Binding of the enzyme to alginate in a pH at which the alginate is in its swollen state (slightly above its pKa)-i.e., not dissolved and not in its collapse/insolubility state-seems to be the perfect combination to match with the pH of optimal enzyme stability. Finally, it has been also observed that the strong loss in activity at lower pHs around pH 2-3 at 60-70 • C are most likely caused by enzyme instability, as thermal stability analyses showed that the Tm of the enzyme under these conditions hovers around or below the usually reported temperature (Tm is 50-60 • C) [63]. Then, the reduction in activity at lower temperatures 20-40 • C (supposed to be below Tm) and pH 5-6 is probably not related to instability, as Tm is much higher under these conditions.…”

Section: Optimization For High Catalytic Activity Of the Encapsulatedmentioning

confidence: 99%

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Biodegradation of Crystalline Cellulose Nanofibers by Means of Enzyme Immobilized-Alginate Beads and Microparticles

et al. 2020

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Recent advances in nanocellulose technology have revealed the potential of crystalline cellulose nanofibers to reinforce materials which are useful for tissue engineering, among other functions. However, the low biodegradability of nanocellulose can possess some problems in biomedical applications. In this work, alginate particles with encapsulated enzyme cellulase extracted from Trichoderma reesei were prepared for the biodegradation of crystalline cellulose nanofibers, which carrier system could be incorporated in tissue engineering biomaterials to degrade the crystalline cellulose nanoreinforcement in situ and on-demand during tissue regeneration. Both alginate beads and microparticles were processed by extrusion-dropping and inkjet-based methods, respectively. Processing parameters like the alginate concentration, concentration of ionic crosslinker Ca2+, hardening time, and ionic strength of the medium were varied. The hydrolytic activity of the free and encapsulated enzyme was evaluated for unmodified (CNFs) and TEMPO-oxidized cellulose nanofibers (TOCNFs) in suspension (heterogeneous conditions); in comparison to solubilized cellulose derivatives (homogeneous conditions). The enzymatic activity was evaluated for temperatures between 25–75 °C, pH range from 3.5 to 8.0 and incubation times until 21 d. Encapsulated cellulase in general displayed higher activity compared to the free enzyme over wider temperature and pH ranges and for longer incubation times. A statistical design allowed optimizing the processing parameters for the preparation of enzyme-encapsulated alginate particles presenting the highest enzymatic activity and sphericity. The statistical analysis yielded the optimum particles characteristics and properties by using a formulation of 2% (w/v) alginate, a coagulation bath of 0.2 M CaCl2 and a hardening time of 1 h. In homogeneous conditions the highest catalytic activity was obtained at 55 °C and pH 4.8. These temperature and pH values were considered to study the biodegradation of the crystalline cellulose nanofibers in suspension. The encapsulated cellulase preserved its activity for several weeks over that of the free enzyme, which latter considerably decreased and practically showed deactivation after just 10 d. The alginate microparticles with their high surface area-to-volume ratio effectively allowed the controlled release of the encapsulated enzyme and thereby the sustained hydrolysis of the cellulose nanofibers. The relative activity of cellulase encapsulated in the microparticles leveled-off at around 60% after one day and practically remained at that value for three weeks.

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“…It is essential to consider that every single enzyme has its own optimal temperature, which usually tends to be superior to their maximum stability temperature. Thus, it is necessary to find a consensus between both values [91,92]. Another important aspect of this enzymatic reaction is the pH, whose operational value ranges from 3 to 5 [93].…”

Section: Temperature and Phmentioning

confidence: 99%

Production of Oligosaccharides from Agrofood Wastes

et al. 2020

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The development of biorefinery processes to platform chemicals for most lignocellulosic substrates, results in side processes to intermediates such as oligosaccharides. Agrofood wastes are most amenable to produce such intermediates, in particular, cellooligo-saccharides (COS), pectooligosaccharides (POS), xylooligosaccharides (XOS) and other less abundant oligomers containing mannose, arabinose, galactose and several sugar acids. These compounds show a remarkable bioactivity as prebiotics, elicitors in plants, food complements, healthy coadyuvants in certain therapies and more. They are medium to high added-value compounds with an increasing impact in the pharmaceutical, nutraceutical, cosmetic and food industries. This review is focused on the main production processes: autohydrolysis, acid and basic catalysis and enzymatic saccharification. Autohydrolysis of food residues at 160-190 • C leads to oligomer yields in the 0.06-0.3 g/g dry solid range, while acid hydrolysis of pectin (80-120 • C) or cellulose (45-180 • C) yields up to 0.7 g/g dry polymer. Enzymatic hydrolysis at 40-50 • C of pure polysaccharides results in 0.06-0.35 g/g dry solid (DS), with values in the range 0.08-0.2 g/g DS for original food residues.Fermentation 2020, 6, 31 2 of 27 forestall engineering approaches, to name a few. Lignocellulosic biomass, of any origin is, therefore, a most promising raw material for biorefineries, considering such facilities as integrated refineries turning biomass into fuels, platform chemicals, food, feed and materials using integrated processes with an optimized used of resources [4]. This vision can be extended to resources of aquatic origin (seaweed, seagrass and microalgae) as well as residues from livestock [5,6]. In general, apart from forestall and energy crops biomass, most of it depends on the production of biomass and, in particular, food wastes [7,8]. While more than 100,000 M tons of biomass wastes are yearly produced [7], wastes strictly considered as food wastes (foods not consumed from any part of the food supply chain or any part of the food that is non edible and, therefore, becomes a residue) account for more than 1300 M tons each year [8]. The valorization of biomass wastes into a plethora of useful energy vectors, chemical compounds and ingredients receives a notable amount of interest from all stakeholders, including researchers and entrepreneurs. They are a source to several value-added products, such as monosaccharides (glucose, xylose, mannose, fructose, arabinose and more), oligosaccharides (fructoor FOS, xylo-or XOS, galacto-or GOS, galacturonic-or GALOS, lactosucrose, etc.), biofuels (ethanol, butanol, dimethylether -DME-, biodiesel, hydrogen), bioactive compounds (flavonoids, phenolic acids, terpenes, terpenoids, carotenoids), nanocellulose (bacterial, wood-related), lignin and its derivatives (a source of aromatics from biomass and prospective substitute of the aromatic or BTEX fraction produced in oil refineries) [8]. Oligomers from cellulose, hemicellulose, lignin, pectin and oth...

show abstract

pH profiles of cellulases depend on the substrate and architecture of the binding region

Cited by 7 publications

References 51 publications

Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives

Enzymatic processing of lignocellulosic biomass: principles, recent advances and perspectives

Biodegradation of Crystalline Cellulose Nanofibers by Means of Enzyme Immobilized-Alginate Beads and Microparticles

Production of Oligosaccharides from Agrofood Wastes

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