Hydrolysis Of Cellulose Research Articles

Thiol-Surface-Engineered Cellulose Nanocrystals in Favor of Copper Ion Uptake.

Cellulose, the most abundant natural polymer on earth, has recently gained attention for a large spectrum of applications. At a nanoscale, nanocelluloses (mainly involving cellulose nanocrystals or cellulose nanofibrils) possess many predominant features, such as highly thermal and mechanical stability, renewability, biodegradability and non-toxicity. More importantly, the surface modification of such nanocelluloses can be efficiently obtained based on the native surface hydroxyl groups, acting as metal ions chelators. Taking into account this fact, in the present work, the sequential process involving chemical hydrolysis of cellulose and autocatalytic esterification using thioglycolic acid was performed to obtain thiol-functionalized cellulose nanocrystals. The change in chemical compositions was attributed to thiol-functionalized groups and explored via the degree of substitution using a back titration method, X-ray powder diffraction, Fourier-transform infrared spectroscopy and thermogravimetric analysis. Cellulose nanocrystals were spherical in shape and ca. 50 nm in diameter as observed via transmission electron microscopy. The adsorption behavior of such a nanomaterial toward divalent copper ions from an aqueous solution was also assessed via isotherm and kinetic studies, elucidating a chemisorption mechanism (ion exchange, metal chelation and electrostatic force) and processing its operational parameters. In contrast to an inactive configure of unmodified cellulose, the maximum adsorption capacity of thiol-functionalized cellulose nanocrystals toward divalent copper ions from an aqueous solution was 4.244 mg g-1 at a pH of 5 and at room temperature.

Production of nanocellulose using controlled acid hydrolysis from large-scale production of micro-fibrillated cellulose derived from oil palm empty fruit bunches

Nanocellulose is generally known as a versatile material, which is suitable for various applications due to its unique physicochemical properties, including light weight, ease of tunable surface functionalization, and excellent mechanical properties. This research aims to characterize and synthesize nanocellulose produced from acid hydrolysis of large-scaled micro-fibrillated cellulose (MFC) derived from oil palm empty fruit bunches by varying concentrations of H2SO4 from 20 to 35 v/v %. The obtained large-scaled MFC had a density of 1.01 kg/m3 and was dominantly composed of 71% cellulose. After acid hydrolysis of MFC, there were gradual changes in the colour of the obtained cellulose nanocrystals (CNC) dispersion from light white to a darker color with the increase of acid concentration, in which the over hydrolysis occurs at 35% of acid concentration. The use of 25-30% H2SO4 showed the optimum condition to avoid over-hydrolysis and resulted in bright white color of CNC dispersion with excellent stability at zeta potential value of -74.2±0.1 to -88.4±0.2 mV. It was supported by Fourier transform infrared (FTIR) due to the presence of negatively charged sulfonyl and hydroxyl groups upon CNC formation to offer excellent dispersion stability. Based on transmission electron microscope (TEM), rod-like shape CNC with a low aspect ratio of 11.8 at the dimension of 12.8 ± 6.7 nm in width and 151.9 ± 38.3 nm in length was successfully produced. Based on X-ray diffraction (XRD) analysis, the crystallinity of the sample was 76%.

Effect and application of proline metabolism-related gene CgMCUR1 on stress tolerance of Candida glycerinogenes and Saccharomyces cerevisiae.

To investigate the effect of CgMCUR1 on the phenotype of Candida glycerinogenes and Saccharomyces cerevisiae. Inhibition of CgMCUR1 expression reduced acetate, H2O2, and high temperature tolerance of C. glycerinogenes. Expression of CgMCUR1 resulted in better acetic acid, H2O2, and high temperature tolerance in recombinant S. cerevisiae. Meanwhile, CgMCUR1 was able to enhance intracellular proline accumulation. The qRT-PCR analysis revealed that overexpression of CgMCUR1 affected proline metabolism in recombinant S. cerevisiae. The overexpression strain also showed reduced levels of cellular lipid peroxidation and an altered ratio of saturated fatty acid (SFA) to unsaturated fatty acid (UFA) in the cell membrane. The ethanol production of recombinant S. cerevisiae at high temperature was 30.9g l-1, obtaining an increase of 12%, and the conversion rate was increased by 12%. In the undetoxified cellulose hydrolysate, the ethanol yield was 14.7g l-1 at 30h with an improvement of 18.5%, and the conversion rate was increased by 15.3%. Overexpression of CgMCUR1 rendered the acetic acid, H2O2, and high temperature tolerant of recombinant S. cerevisiae and enhanced the ethanol fermentation performance of recombinant S. cerevisiae under high temperature stress and in undetoxified cellulose hydrolysate by improving intracellular proline accumulation and by changing cellular physiological metabolism.

CAOSA-extracted lignin improves enzymatic hydrolysis of cellulose

The conversion of biomass into sugar platform compounds is very important for the biorefinery industry. Pretreatment is essential to the biomass of the sugar platform, however, the lignin obtained by pretreatment, as a key part of lignocellulose, generally has a passive effect on the enzymatic hydrolysis of cellulose into sugars. In this study, p-TsOH (p-toluenesulfonic acid), DES (Deep eutectic solvent) and CAOSA (cooking with active oxygen and solid alkali) pretreatment ways were used to fraction lignin from bamboo biomass. After CAOSA treatment, the hydrolysis efficiency of the pulp was 95.57%. Moreover, the effect of different treatment methods on lignin properties was studied and the promotion effect of lignin was investigated by adding it to the cellulose enzymatic hydrolysis system. In this work, the results showed that CAOSA-extracted lignin with lower Đ (1.31–1.25) had a better adsorption effect on the enzyme protein. p-TsOH-extracted lignin with a larger S/G ratio enhanced the inhibition of enzymatic hydrolysis. In addition, the presence of -COOHs in lignin could reduce its inhibitory effect on cellulose saccharification.

Production of cellulases from Amazonian fungi and their application in babassu cellulose hydrolysis

Two Amazonian fungi strains — Aspergillus sp. A1C2-06 and Talaromyces verruculosus A1C2-05 — were studied about their potential as cellulase producers and theis applications in the saccharification of sugarcane bagasse and babassu lignocellulosic biomass. For the cellulase production was studied the influence of cultivation parameters during the solid-state fermentation. The best initial pH were 3,0 and 7,0 for T. verruculosus and Aspergillus sp., respectively, and the optimum temperature was 35 °C for both strains. The ideal Mandel’ solution volume was 7,5 ml and 10,0 ml for T. verruculosus and Aspergillus sp., respectively. The optimal conditions during the hydrolysis of filter paper cellulose were determined, being 2,8 the optimal pH for both cellulases and the optimal temperature were 50 °C and 60 °C for Aspergillus sp and T. verruculosus, respectively. The cellulases from both Aspergillus sp and T. verruculosus were capable of hydrolyzing the lignocellulosic biomasses but in different degree of saccharification. The saccharification degree for both pretreated biomasses reached 80% when cellulases from T. verruculosus were applied for 72h, while the untreated biomasses reached only 60% for babassu and 50% for sugarcane bagasse, indicating that the removal of lignin has an important role in the process of biomass saccharification.

Microbial degradation of kelp waste by cooperation of alginate and cellulose hydrolyzing bacteria: A potential solution for kelp waste reutilization

Microbial degradation of kelp waste by cooperation of alginate and cellulose hydrolyzing bacteria: A potential solution for kelp waste reutilization

Effect of salt addition on cellulose conversion into 5-hydroxymethylfurfural in metal chloride aqueous solution

Metal chloride aqueous solution is an effective method to promote the conversion of cellulose into 5-hydroxymethylfurfural (HMF). In this work, the influences of sodium chloride (NaCl) and lithium chloride (LiCl) on the conversion of cellulose into HMF in ferric chloride (FeCl3) aqueous solution were investigated. The conversion of glucose and fructose in FeCl3–NaCl and FeCl3–LiCl aqueous solutions were studied, and the interaction between active species and cellobiose was characterized by UV spectrum and electrospray ion mass spectrometry to explore salt addition on the reaction of cellulose conversion and the active specie. Results showed that the yield of HMF converted from cellulose in FeCl3 aqueous solution was low, while the yield of HMF was significantly increased when NaCl or LiCl added to the system. In FeCl3–NaCl aqueous solutions, the yield of HMF reach a maximum of 40.0% at a concentration of 0.02 M FeCl3, and hydrolysis of cellulose was the key step in the conversion of cellulose; In FeCl3–LiCl aqueous solutions, the yield of HMF reach a maximum of 36.7% at a concentration of 0.06 M FeCl3, and isomerization of glucose was the controlling step. The characterization results illustrated that the addition of NaCl or LiCl changed the active species in FeCl3 aqueous solutions, and [Fe(OH)2]+ and [FeCl2(OH) + Li]+ were the active species in FeCl3–NaCl and FeCl3–LiCl aqueous solution for cellulose conversion, respectively.

Ethanol from cellulose and cellobiose of woody-substrates in a single stage of 3-combined-bioprocesses employing a non-GM yeast cell-factory

The present study aims to prepare a Saccharomyces cerevisiae cell factory, to combine three bioprocesses in a single stage, including cellulolytic enzyme production, cellulose hydrolysis to glucose, and fermentation with low cost of nutrients to ethanol, without any genetic modification. Cell factories are prepared, in which S. cerevisiae cells are covered with starch gel (SG), either containing Trichoderma reesei (SG-T. reesei), or cellulase produced from T. reesei (SG-cellulase). The work comprises the cellulose bioconversion using S. cerevisiae/SG-cellulase, and S. cerevisiae/SG-T. reesei to carry out alcoholic fermentation in one batch with low nutrient cost. In addition, the effect of different concentrations of yeast in the cell factory on fermentation rate was examined. SEM, FTIR spectra analysis and cellulose fermentation were used to prove the successful preparation of cell factory and its activity to ferment cellulose in one combined bioprocess. The cellulose sourced from delignified sawdust was characterized with XRD spectra and porosimetry analysis. Cell factory models of S. cerevisiae/SG-T. reesei and S. cerevisiae/SG-cellulase were able to ferment cellulose from wood, obtaining 32% and 62% ethanol production yield, respectively. S. cerevisiae/SG-T. reesei and S. cerevisiae/SG-cellulase resulted to 4.07 and 7.30 mL ethanol/L, respectively. The final glucose concentration was very low (0–0.07 g glucose/L). It is also concluded that the increase of S. cerevisiae concentration in CF helped an improvement in the bioconversion process.

Heterologous Expression and Biochemical Characterization of a Thermostable Endoglucanase (MtEG5-1) from Myceliophthora thermophila

Thermophilic endoglucanases have become of significant interest for effectively catalyzing the hydrolysis of cellulose. Myceliophthora thermophila is an ideal source of thermophilic enzymes. Interestingly, different hosts differently express the same enzymes. In this study, we successfully overexpressed endoglucanase (MtEG5-1) from M. thermophila in the methylotrophic yeast, Pichia pastoris GS115, via electroporation. We found that purified MtEG5-1 exhibited optimum activity levels at pH 5 and 70 °C, with 88% thermal stability after being incubated at 70 °C for 2 h. However, we observed that purified MtEG5-1 had a molecular weight of 55 kDa. The Km and Vmax values of purified MtEG5-1 were approximately 6.11 mg/mL and 91.74 μmol/min/mg at 70 °C (pH 5.0), respectively. Additionally, the optimum NaCl concentration of purified MtEG5-1 was found to be 6 g/L. Furthermore, we observed that the activity of purified MtEG5-1 was significantly enhanced by Mn2+ and was inhibited by K+. These results indicated that MtEG5-1 expressed by P. pastoris GS115 is more heat-tolerant than that expressed by A. niger and P. pastoris X33. These properties of MtEG5-1 make it highly suitable for future academic research and industrial applications.

Effect and mechanism analysis of dual enzyme pretreatment on enhancement of volatile fatty acids production in kitchen waste anaerobic acidification

The high content of cellulose and hemicellulose in kitchen waste (KW) results in a slow hydrolysis rate and subsequently hinders the yields of volatile fatty acids (VFAs) in anaerobic acidification. In this study, cellulase and hemicellulase were used for the pretreatments of KW to tackle the problem of difficult hydrolysis in anaerobic acidification. The results indicated that the joint use of double enzymes significantly improved the hydrolysis of cellulose and hemicellulose during pretreatment, thus enhancing the VFAs production in anaerobic acidification. The highest production of TVFAs was 50.73 ± 2.10 g COD/L and it was improved by 62.77% compared with the unpretreated group. In addition, the 16S rRNA amplicon sequencing analysis showed that the relative abundance of Firmicutes related with the VFAs production increased from 17.77% to 50.55%. The potential metabolism function analysis (PICRUSt2) indicated that the enrichment of glyceraldehyde-3-phosphate dehydrogenase (EC:1.2.1.9) and acetyl-CoA C-acetyltransferase (EC:2.3.1.9) contributed to the production of VFAs in AD. The results suggested that collaborative enzyme pretreatment could be one of the effective methods for the hydrolysis of cellulose and hemicellulose in KW and provided constructive mechanistic insights into recovering valuable products from KW.

Genetic modification of Escherichia coli to improve 1,2,4-butanetriol production from cellulose hydrolysate

Genetic modification of Escherichia coli to improve 1,2,4-butanetriol production from cellulose hydrolysate

Production of Cellulase by Trichoderma viride via Submerged Fermentation using Corncob as Substrate

Cellulolytic enzymes are commonly used in lignocellulosic biomass conversion, textile, and paper and pulp industries. However, the high cost of cellulase and the high demand has led to increase researches to explore agro-residues for cost-effective production. This study was aimed at isolating Trichoderma viride from decaying wood and soil, and testing the isolates for cellulase production via submerged fermentation using corncob as substrate. Twenty-one (21) soil samples were collected from three different locations (botanical garden, refuse dump site and decaying wood) and used in the study. Colonies suspected to be Trichoderma viride were identified by microscopy of lactophenol cotton blue-stained preparation and slide culture technique, respectively. Isolates confirmed to be Trichoderma viride were then screened for cellulase production on a mineral salt medium containing carboxymethyl cellulose as an inducer. The isolates were further tested for cellulase production using corncob as the substrate via submerged fermentation. Out of the 21 samples analysed, 4 (19%) were positive for Trichoderma viride based on cultural and microscopic characteristics. The highest occurrence of Trichoderma viride (57%) was recorded from decaying wood samples, while no occurrence (0%) was observed from the botanical garden and refuse dumpsite soils. All four isolates obtained produced cellulase, with T. viride DW6 having the highest zone of cellulose hydrolysis (61.5 ± 2.12 mm) and T. viride DW1 having the least (58.5 ± 2.12 mm). The highest enzyme activity was recorded from T. viride DW4 (3.41 ± 0.46 U/ml) and the lowest from T. viride DW1 (1.77 ± 0.52 U/ml) using corncob as substrate. Trichoderma viride is abundantly present in decaying wood, and such isolates have high cellulase-producing ability, as wood material is rich in cellulose. This preliminary study provides information on the isolation of T. viride from decaying wood and their potential for cellulase production using corncob as substrate.

Biochemical conversion of waste paper slurries into bioethanol

Waste papers, which are a major constituent of municipal wastes, can be repurposed into the production of bioethanol, a renewable and ecofriendly fuel. Many studies have produced ethanol from print-grade papers, but literature on conversion of waste cartons is sparce. In this study, waste corrugated cartons and print-grade papers were reduced into slurries and were subjected to physical and chemical tests to determine their suitability for biosynthesis. Cellulose fibers in the slurries were directly hydrolyzed into glucose without prior pretreatment by dilute hydrochloric acid, and fermented into ethanol using Saccaromyces cerevisae. Density, flammability, color, odor, non-volatile residue and other qualitative tests were conducted on the ethanol produced. Glucose yield and the extraction efficiency in cellulose hydrolysis were significantly higher for waste cartons than print paper slurries. Qualitative tests reveal that the ethanol produced from both slurries has physical and chemical characteristics that are comparable to laboratory grade ethanol, contains no toxic impurities, and is suitable for use as a biofuel.

Cellulose esterification with carboxylic acid in deep eutectic solvent pretreatment inhibits enzymatic hydrolysis

Avicel cellulose was pretreated using two commonly used carboxylic acid-based deep eutectic solvents, i.e., choline chloride-lactic acid and choline chloride-formic acid. The pretreatment process resulted in the formation of cellulose esters with lactic acid and formic acid, which was confirmed by infrared and nuclear magnetic resonance spectra. Surprisingly, the esterified cellulose led to a significant decrease in the 48-h enzymatic glucose yield (≥75%) compared to raw Avicel cellulose. Analysis of changes in cellulose properties caused by pretreatment, including crystallinity, degree of polymerization, particle size and cellulose accessibility, contradicted the observed decline in enzymatic cellulose hydrolysis. However, removing the ester groups through saponification largely recovered the reduction in cellulose conversion. The decreased enzymatic cellulose hydrolysis by esterification may be attributed to changes in the interaction between cellulose-binding domain of cellulase and cellulose. These findings provide valuable insights into improving the saccharification of lignocellulosic biomass pretreated by carboxylic acid-based DESs.

Simultaneous removal of methylene blue, copper Cu(II), and cadmium Cd(II) from synthetic wastewater using fennel-based adsorbents

Abstract This work looked into viability of using fennel-based adsorbents to simultaneously eliminate cadmium, methylene blue, and copper from water solution. Phosphoric acid (H3PO4) and calcium hydroxide (Ca(OH)2) solutions were applied to the untreated fennel seeds (PFS) to yield H3FS and CaFS, respectively. The presence of –OH, –C–O–C–, and –C=O functional groups on the surface of the adsorbents was confirmed by FTIR results. XRD and UV–Vis results established hydrolysis of cellulose from fennel seeds. According to studies on time and kinetics, the adsorption process was relatively quick in the first 60 min. Furthermore, isotherm models showed that the results fit Langmuir model more closely. This finding indicated that uptake takes place on uniform active sites on adsorbent surfaces. Studies on thermodynamics showed that the adsorption procedure was advantageous and practicable. PFS, H3FS, and CaFS had maximum Cu(II) adsorption capacities of 7.208, 5.504, and 5.791 mg/g. It was 2.274, 5.021, and 12.3 mg/g for Cd(II) by PFS, H3FS, and CaFS. PFS, H3FS, and CaFS could adsorb MB to a maximum of 11.114, 4.071, and 18.468 mg/g. Reusability studies of the adsorbents were also evaluated and the results suggested that the adsorbents can be recycled a number of times.

Cellulases: From Lignocellulosic Biomass to Improved Production

Cellulases are enzymes that are attracting worldwide attention because of their ability to degrade cellulose in the lignocellulosic biomass and transform it into highly demanded bioethanol. The enzymatic hydrolysis of cellulose by cellulases into fermentable sugars is a crucial step in biofuel production, given the complex structure of lignocellulose. Due to cellulases’ unique ability to hydrolyze the very recaltricant nature of lignocellulosic biomass, the cellulase market demand is rapidly growing. Although cellulases have been used in industrial applications for decades, constant effort is being made in the field of enzyme innovation to develop cellulase mixtures/cocktails with improved performance. Given that the main producers of cellulases are of microbial origin, there is a constant need to isolate new microorganisms as potential producers of enzymes important for biofuel production. This review provides insight into current research on improving microbial cellulase production as well as the outlook for the cellulase market with commercial cellulase preparation involved in industrial bioethanol production.

Low-cost biosorption of Fe(II) and Fe(III) from single and binary solutions using Ulva lactuca-derived cellulose nanocrystals-graphene oxide composite film

The marine algal biomass of Ulva lactuca was utilized for the extraction of cellulose and the development of cellulose nanocrystals/graphene oxide film. Cellulose nanocrystals with 50–150 nm were produced by H2SO4 hydrolysis of the algal cellulose. The adsorption efficiency of the nanocomposite film for Fe(II) and Fe(III) ions was successfully evaluated using Box-Behnken design. The maximum removal for Fe(II) (64.15%) could be attained at pH 5.13, adsorbent dosage 7.93 g L−1 and Fe(II) concentration 15.39 mg L−1, while the biosorption of Fe(III) was 69.92% at pH 5.0, adsorbent dosage 2 g L−1, and Fe(III) concentration 15.0 mg L−1. However, in the binary system, the removal efficiency of Fe(II) was enhanced to 95.48% at Fe(II):Fe(III) ratio of 1:1, while the Fe(III) removal was increased to 79.17% at ratio 1:2. The pseudo-second-order kinetics exhibited better fitting to the experimental results of Fe(II) and Fe(III) adsorption in both single and binary systems. The intra-particle diffusion was prominent during the biosorption, but the effect of the external mass transfer was significant. The Langmuir, Freundlich, Langmuir–Freundlich, Temkin, and Dubinin-Radushkevich isotherms showed satisfactory fitting to the experimental data, but they differ in priority based on iron state and pH. The adsorption of Fe(II) in the presence of Fe(III) in a mixture was best represented by the extended Langmuir model, while the extended Langmuir–Freundlich model best fitted the adsorption of Fe(III). The FT-IR analysis indicated that physisorption through electrostatic interaction/complexation is the predominant mechanism for the adsorption of iron using the nanocomposite film.

Interactions between cellulose and lignin during hydrolysis in subcritical water

The interactions between cellulose and lignin, and the hydrolysis behavior of cellulose, lignin and cellulose-lignin mixtures with mass ratios of 25/75, 50/50, 75/25 in subcritical water were investigated in this study. Cellulose and lignin interactions greatly promoted the hydrolysis of lignin during hydrolysis of the cellulose-lignin mixture with a mass ratio of 25/75, whereas they accelerated and suppressed lignin hydrolysis in the other cellulose-lignin mixtures at reaction temperatures under and above 257 °C, respectively. The cellulose and lignin interactions presented negative effects on cellulose hydrolysis in all the samples at reaction temperatures higher than 257 °C. However, they showed positive and negative effects in the cellulose-lignin mixture with a mass ratio of 25/75, and the cellulose-lignin mixtures with mass ratios of 50/50 and 75/25, respectively, at reaction temperatures under 257 °C. The cellulose and lignin interactions also suppressed the heat-related reactions and the glucose and aromatic-linked polymer char formation reactions.

Isolation and pan-genome analysis of Enterobacter hormaechei Z129, a ureolytic bacterium, from the rumen of dairy cow.

Urea is an important non-protein nitrogen source for ruminants. In the rumen, ureolytic bacteria play critical roles in urea-nitrogen metabolism, however, a few ureolytic strains have been isolated and genomically sequenced. The purpose of this study was to isolate a novel ureolytic bacterial strain from cattle rumen and characterize its genome and function. The ureolytic bacterium was isolated using an anaerobic medium with urea and phenol red as a screening indicator from the rumen fluid of dairy cattle. The genome of isolates was sequenced, assembled, annotated, and comparatively analyzed. The pan-genome analysis was performed using IPGA and the biochemical activity was also analyzed by test kits. A gram-positive ureolytic strain was isolated. Its genome had a length of 4.52 Mbp and predicted genes of 4223. The 16S rRNA gene and genome GTDB-Tk taxonomic annotation showed that it was a novel strain of Enterobacter hormaechei, and it was named E. hormaechei Z129. The pan-genome analysis showed that Z129 had the highest identity to E. hormaechei ATCC 49162 with a genome average nucleotide identity of 98.69% and possessed 238 unique genes. Strain Z129 was the first E. hormaechei strain isolated from the rumen as we know. The functional annotation of the Z129 genome showed genes related to urea metabolism, including urea transport (urtA-urtE), nickel ion transport (ureJ, tonB, nixA, exbB, exbD, and rcnA), urease activation (ureA-ureG) and ammonia assimilation (gdhA, glnA, glnB, glnE, glnL, glsA, gltB, and gltD) were present. Genes involved in carbohydrate metabolism were also present, including starch hydrolysis (amyE), cellulose hydrolysis (celB and bglX), xylose transport (xylF-xylH) and glycolysis (pgi, pgk, fbaA, eno, pfkA, gap, pyk, gpmL). Biochemical activity analysis showed that Z129 was positive for alkaline phosphatase, leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase, α-glucosidase, β-glucosidase, and pyrrolidone arylaminase, and had the ability to use D-ribose, L-arabinose, and D-lactose. Urea-nitrogen hydrolysis rate of Z129 reached 55.37% at 48 h of incubation. Therefore, the isolated novel ureolytic strain E. hormaechei Z129 had diverse nitrogen and carbon metabolisms, and is a preferred model to study the urea hydrolysis mechanism in the rumen.

Biochemical and structural characterisation of a family GH5 cellulase from endosymbiont of shipworm P. megotara

BackgroundCellulases play a key role in the enzymatic conversion of plant cell-wall polysaccharides into simple and economically relevant sugars. Thus, the discovery of novel cellulases from exotic biological niches is of great interest as they may present properties that are valuable in the biorefining of lignocellulosic biomass.ResultsWe have characterized a glycoside hydrolase 5 (GH5) domain of a bi-catalytic GH5-GH6 multi-domain enzyme from the unusual gill endosymbiont Teredinibacter waterburyi of the wood-digesting shipworm Psiloteredo megotara. The catalytic GH5 domain, was cloned and recombinantly produced with or without a C-terminal family 10 carbohydrate-binding module (CBM). Both variants showed hydrolytic endo-activity on soluble substrates such as β-glucan, carboxymethylcellulose and konjac glucomannan, respectively. However, low activity was observed towards the crystalline form of cellulose. Interestingly, when co-incubated with a cellulose-active LPMO, a clear synergy was observed that boosted the overall hydrolysis of crystalline cellulose. The crystal structure of the GH5 catalytic domain was solved to 1.0 Å resolution and revealed a substrate binding cleft extension containing a putative + 3 subsite, which is uncommon in this enzyme family. The enzyme was active in a wide range of pH, temperatures and showed high tolerance for NaCl.ConclusionsThis study provides significant knowledge in the discovery of new enzymes from shipworm gill endosymbionts and sheds new light on biochemical and structural characterization of cellulolytic cellulase. Study demonstrated a boost in the hydrolytic activity of cellulase on crystalline cellulose when co-incubated with cellulose-active LPMO. These findings will be relevant for the development of future enzyme cocktails that may be useful for the biotechnological conversion of lignocellulose.