Quantifying Oxidation of Cellulose-Associated Glucuronoxylan by Two Lytic Polysaccharide Monooxygenases from Neurospora crassa

Enhancing cellulase production in Neurospora crassa through combined deletion of the phospholipase D-encoding gene pla-7 and modulation of transcription factor CLR-2 expression

Neurospora crassa, a saprophytic fungus, naturally secretes plant cell wall-degrading enzymes, demonstrating strong cellulases production. Despite its century-long use as a model organism, its industrial applications are underexplored. We compared N. crassa with Trichoderma reesei, an industrial workhorse, for cellulases production and lignocellulose degradation. The extracellular protein secretion level of N. crassa WT is significantly higher than that of T. reesei QM6a, indicating industrial potential. However, its mycelial morphology and dependence on insoluble substrates like lignocellulose pose bioreactor challenges. Deleting the phospholipase D gene pla-7 in N. crassa resulted in shorter aerial hyphae, increased branching, and improved biomass on sucrose. Although pla-7 deletion hindered cellulase induction on cellulose in shake flasks, mis-expressing clr-2 restored cellulase production in Δpla-7 strains. Additionally, protein secretion levels in Δpla-7::Mclr-2 strains were approximately doubled on both sucrose and cellulose carbon sources compared to WT::Mclr-2 strains in shake flasks. Furthermore, Δpla-7::Mclr-2 strains demonstrated enhanced fermentation properties in bioreactors using sucrose. These results highlight N. crassa' s industrial promise and provide insights for enhancing production of cellulases in other fungi.

Functional characterization of two AA10 lytic polysaccharide monooxygenases from Cellulomonas gelida

Lytic polysaccharide monooxygenases (LPMOs) are redox enzymes targeting the crystalline region of recalcitrant polysaccharides such as cellulose and chitin. Functional characterization of two LPMOs from the cellulose-degrading soil bacterium Cellulomonas gelida, CgLPMO10A and CgLPMO10B, showed expected activities on cellulose but also revealed novel features of AA10 LPMOs. While clustering together with strictly C1-oxidizing and strictly cellulose-active AA10 LPMOs, CgLPMO10A exhibits activity on both cellulose and chitin, oxidizing the C1 carbon of both substrates. This combination of substrate and oxidative specificity has not been previously observed for family 10 LPMOs and may be due to a conspicuous divergence in two hydrophobic residues on the substrate-binding surface. CgLPMO10B oxidizes cellulose at both the C1 and C4 positions and is also active on chitin, in line with predictions based on phylogeny. Interestingly, while coming from the same organism and both acting on cellulose, the two enzymes have markedly different redox properties with CgLPMO10B displaying the lowest redox potential and the highest oxidase activity observed for an AA10 LPMO so far. These results provide insight into the LPMO machinery of C. gelida and expand the known catalytic repertoire of bacterial LPMOs.

A modular enzyme with combined hemicellulose-removing and LPMO activity increases cellulose accessibility in softwood

Because of the association with other complex polysaccharides, extracting and utilizing cellulose from lignocellulosic materials requires the combined action of a broad range of carbohydrate-active enzymes, including multiple glycoside hydrolases (GHs) and lytic polysaccharide monooxygenases (LPMOs). The interplay between these enzymes and the way in which Nature orchestrates their co-existence and combined action are topics of great scientific and industrial interest. To gain more insight into these issues, we have studied the lignocellulose-degrading abilities of an enzyme from Caldibacillus cellulovorans (CcLPMO10-Man5), comprising an LPMO domain, a GH5 mannanase domain and two family 3 carbohydrate-binding modules (CBM3). Using a natural softwood substrate, we show that this enzyme promotes cellulase activity, i.e., saccharification of cellulose, both by removing mannan covering the cellulose and by oxidatively breaking up the cellulose structure. Synergy with CcLPMO10-Man5 was most pronounced for two tested cellobiohydrolases, whereas effects were smaller for a tested endoglucanase, which is in line with the notion that cellobiohydrolases and LPMOs attack the same crystalline regions of the cellulose, whereas endoglucanases attack semi-crystalline and amorphous regions. Importantly, the LPMO domain of CcLPMO10-Man5 is incapable of accessing the softwood cellulose in absence of the mannanase domain. Considering that LPMOs not bound to a substrate are sensitive to autocatalytic inactivation, this intramolecular synergy provides a perfect rationale for the evolution of modular enzymes such as CcLPMO10-Man5. The intramolecular coupling of the LPMO with a mannanase and two CBMs ensures that the LPMO is directed to areas where mannans are removed and cellulose thus becomes available.

Enzymatic Routes to Designer Hemicelluloses for Use in Biobased Materials

Various enzymes can be used to modify the structure of hemicelluloses directly in vivo or following extraction from biomass sources, such as wood and agricultural residues. Generally, these enzymes can contribute to designer hemicelluloses through four main strategies: (1) enzymatic hydrolysis such as selective removal of side groups by glycoside hydrolases (GH) and carbohydrate esterases (CE), (2) enzymatic cross-linking, for instance, the selective addition of side groups by glycosyltransferases (GT) with activated sugars, (3) enzymatic polymerization by glycosynthases (GS) with activated glycosyl donors or transglycosylation, and (4) enzymatic functionalization, particularly via oxidation by carbohydrate oxidoreductases and via amination by amine transaminases. Thus, this Perspective will first highlight enzymes that play a role in regulating the degree of polymerization and side group composition of hemicelluloses, and subsequently, it will explore enzymes that enhance cross-linking capabilities and incorporate novel chemical functionalities into saccharide structures. These enzymatic routes offer a precise way to tailor the properties of hemicelluloses for specific applications in biobased materials, contributing to the development of renewable alternatives to conventional materials derived from fossil fuels.

Characterization of a novel AA16 lytic polysaccharide monooxygenase from Thermothelomyces thermophilus and comparison of biochemical properties with an LPMO from AA9 family

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes which are categorized in the CAZy database under auxiliary activities families AA9-11, 13, 14-17. Secreted by various microorganisms, they play a crucial role in carbon recycling, particularly in fungal saprotrophs. LPMOs oxidize polysaccharides through monooxygenase/peroxygenase activities and exhibit peroxidase and oxidase activities, with variations among different families. AA16, a newly identified LPMO family, is noteworthy due to limited studies on its members, thus rendering the characterization of AA16 enzymes vital for addressing controversies around their functions. This study focused on heterologous expression and biochemical study of an AA16 LPMO from Thermothelomyces thermophilus (formerly known as Myceliophthora thermophila), namely MtLPMO16A. Substrate specificity evaluation of MtLPMO16A showed oxidative cleavage of hemicellulosic substrates and no activity on cellulose, accompanied by a strong oxidase activity. A comparative analysis with an LPMO from AA9 family explored correlations between these families, while MtLPMO16A was shown to boost the activity of some AA9 family LPMOs. The results offer new insights into the AA16 family's action mode and microbial hemicellulose decomposition mechanisms in nature.

Genomic characterization and expression profiling of the lytic polysaccharide monooxygenases AA9 family in thermophilic fungi Thermothelomyces fergusii in response to carbon source media

Enhancing enzyme activity and stability in biomass degradation can improve substrate saccharification and, increases biorefinery efficiency. For the first time, we identified 20 lytic polysaccharide monooxygenases (LPMOs) AA9 genes in the genome of Thermothelomyces fergusii. Our results showed that TfAA9 was categorized into LPMOs1, LPMOs2, and LPMOs3 subgroups based on protein diversity. Protein- 3D structure analysis showed strong interactions between Myceliophthora thermophila AA9 proteins and 17 TfAA9 proteins. Gene ontology analysis indicated a high enrichment of cellulase activity in TfAA9 genes. KEGG pathways analysis revealed the role of TfAA9 proteins in the endohydrolysis of 1,4-beta-D-glucosidic linkages in cellulose. Numerous TfAA9s gene transcripts were up-regulated on avicel, cellobiose, and glucose, with a higher proportion on avicel. Protein concentration, endoglucanase, and cellulase activity were also boosted on avicel. However, limited fungal biomass was observed on avicel, despite the abundance of AA9 LPMOs in the T. fergusii genome. These findings expand our understanding of fungal AA9 genes and their role in lignocellulolytic degradation. The disparity between biomass and enzymatic activity suggests screening TfAA9 genes for highly active enzymes and redundant genes via heterologous expression. In short, functional characterization of these genes could contribute to improving the saccharification process of industrial raw materials.

A novel AA14 LPMO from Talaromyces rugulosus with bifunctional cellulolytic/hemicellulolytic activity boosted cellulose hydrolysis

BACKGROUND

The recently discovered PcAA14A and B from white-rot basidiomycete Pycnoporus coccineus enriched our understanding of the oxidative degradation of xylan in fungi, however, the unusual mode of action of AA14 LPMOs has sparked controversy. The substrate specificity and functionality of AA14 LPMOs still remain enigmatic and need further investigation.

RESULTS

In this study, a novel AA14 LPMO was characterized from the ascomycete Talaromyces rugulosus. TrAA14A has a broad substrate specificity with strong oxidative activity on pure amorphous cellulose and xyloglucan. It could simultaneously oxidize cellulose, xylan and xyloglucan in natural hemi/cellulosic substrate such as fibrillated eucalyptus pulp, and released native and oxidized cello-oligosaccharides, xylo-oligosaccharides and xyloglucan oligosaccharides from this substrate, but its cellulolytic/hemicellulolytic activity became weaker as the contents of xylan increase in the alkaline-extracted hemi/cellulosic substrates. The dual cellulolytic/hemicellulolytic activity enables TrAA14A to possess a profound boosting effect on cellulose hydrolysis by cellulolytic enzymes. Structure modelling of TrAA14A revealed that it exhibits a relatively flat active-site surface similar to the active-site surfaces in AA9 LPMOs but quite distinct from PcAA14B, despite TrAA14A is strongly clustered together with AA14 LPMOs. Remarkable difference in electrostatic potentials of L2 and L3 surfaces was also observed among TrAA14A, PcAA14B and NcLPMO9F. We speculated that the unique feature in substrate-binding surface might contribute to the cellulolytic/hemicellulolytic activity of TrAA14A.

CONCLUSIONS

The extensive cellulolytic/hemicellulolytic activity on natural hemi/cellulosic substrate indicated that TrAA14A from ascomycete is distinctively different from previously characterized xylan-active AA9 or AA14 LPMOs. It may play as a bifunctional enzyme to decompose some specific network structures formed between cellulose and hemicellulose in the plant cell walls. Our findings shed new insights into the novel substrate specificities and biological functionalities of AA14 LPMOs, and will contribute to developing novel bifunctional LPMOs as the booster in commercial cellulase cocktails to efficiently break down the hemicellulose-cellulose matrix in lignocellulose.

Electrochemical Monitoring of Heterogeneous Peroxygenase Reactions Unravels LPMO Kinetics

Biological conversion of plant biomass depends on peroxygenases and peroxidases acting on insoluble polysaccharides and lignin. Among these are cellulose- and hemicellulose-degrading lytic polysaccharide monooxygenases (LPMOs), which have revolutionized our concept of biomass degradation. Major obstacles limiting mechanistic and functional understanding of these unique peroxygenases are their complex and insoluble substrates and the hard-to-measure H2O2 consumption, resulting in the lack of suitable kinetic assays. We report a versatile and robust electrochemical method for real-time monitoring and kinetic characterization of LPMOs and other H2O2-dependent interfacial enzymes based on a rotating disc electrode for the sensitive and selective quantitation of H2O2 at biologically relevant concentrations. The H2O2 sensor works in suspensions of insoluble substrates as well as in homogeneous solutions. Our characterization of multiple LPMOs provides unprecedented insights into the substrate specificity, kinetics, and stability of these enzymes. High turnover and total turnover numbers demonstrate that LPMOs are fast and durable biocatalysts.

Functional characterization of a lytic polysaccharide monooxygenase from Schizophyllum commune that degrades non-crystalline substrates

Lytic polysaccharide monooxygenases (LPMOs) are mono-copper enzymes that use O2 or H2O2 to oxidatively cleave glycosidic bonds. LPMOs are prevalent in nature, and the functional variation among these enzymes is a topic of great interest. We present the functional characterization of one of the 22 putative AA9-type LPMOs from the fungus Schizophyllum commune, ScLPMO9A. The enzyme, expressed in Escherichia coli, showed C4-oxidative cleavage of amorphous cellulose and soluble cello-oligosaccharides. Activity on xyloglucan, mixed-linkage β-glucan, and glucomannan was also observed, and product profiles differed compared to the well-studied C4-oxidizing NcLPMO9C from Neurospora crassa. While NcLPMO9C is also active on more crystalline forms of cellulose, ScLPMO9A is not. Differences between the two enzymes were also revealed by nuclear magnetic resonance (NMR) titration studies showing that, in contrast to NcLPMO9C, ScLPMO9A has higher affinity for linear substrates compared to branched substrates. Studies of H2O2-fueled degradation of amorphous cellulose showed that ScLPMO9A catalyzes a fast and specific peroxygenase reaction that is at least two orders of magnitude faster than the apparent monooxygenase reaction. Together, these results show that ScLPMO9A is an efficient LPMO with a broad substrate range, which, rather than acting on cellulose, has evolved to act on amorphous and soluble glucans.

Revisiting the AA14 family of lytic polysaccharide monooxygenases and their catalytic activity

Lytic polysaccharide monooxygenases (LPMOs) belonging to the AA14 family are believed to contribute to the enzymatic degradation of lignocellulosic biomass by specifically acting on xylan in recalcitrant cellulose-xylan complexes. Functional characterization of an AA14 LPMO from Trichoderma reesei, TrAA14A, and a re-evaluation of the properties of the previously described AA14 from Pycnoporus coccineus, PcoAA14A, showed that these proteins have oxidase and peroxidase activities that are common for LPMOs. However, we were not able to detect activity on cellulose-associated xylan or any other tested polysaccharide substrate, meaning that the substrate of these enzymes remains unknown. Next to raising questions regarding the true nature of AA14 LPMOs, the present data illustrate possible pitfalls in the functional characterization of these intriguing enzymes.

Hemicellulolytic enzymes in lignocellulose processing

Lignocellulosic biomass is the most abundant source of carbon-based material on a global basis, serving as a raw material for cellulosic fibers, hemicellulosic polymers, platform sugars, and lignin resins or monomers. In nature, the various components of lignocellulose (primarily cellulose, hemicellulose, and lignin) are decomposed by saprophytic fungi and bacteria utilizing specialized enzymes. Enzymes are specific catalysts and can, in many cases, be produced on-site at lignocellulose biorefineries. In addition to reducing the use of often less environmentally friendly chemical processes, the application of such enzymes in lignocellulose processing to obtain a range of specialty products can maximize the use of the feedstock and valorize many of the traditionally underutilized components of lignocellulose, while increasing the economic viability of the biorefinery. While cellulose has a rich history of use in the pulp and paper industries, the hemicellulosic fraction of lignocellulose remains relatively underutilized in modern biorefineries, among other reasons due to the heterogeneous chemical structure of hemicellulose polysaccharides, the composition of which varies significantly according to the feedstock and the choice of pretreatment method and extraction solvent. This paper reviews the potential of hemicellulose in lignocellulose processing with focus on what can be achieved using enzymatic means. In particular, we discuss the various enzyme activities required for complete depolymerization of the primary hemicellulose types found in plant cell walls and for the upgrading of hemicellulosic polymers, oligosaccharides, and pentose sugars derived from hemicellulose depolymerization into a broad spectrum of value-added products.

H2 O2 feeding enables LPMO-assisted cellulose saccharification during simultaneous fermentative production of lactic acid

Simultaneous saccharification and fermentation (SSF) is a well-known strategy for valorization of lignocellulosic biomass. Because the fermentation process typically is anaerobic, oxidative enzymes found in modern commercial cellulase cocktails, such as lytic polysaccharide monooxygenases (LPMOs), may be inhibited, limiting the overall efficiency of the enzymatic saccharification. Recent discoveries, however, have shown that LPMOs are active under anoxic conditions if they are provided with H₂ O₂ at low concentrations. In this study, we build on this concept and investigate the potential of using externally added H₂ O₂ to sustain oxidative cellulose depolymerization by LPMOs during an SSF process for lactic acid production. The results of bioreactor experiments with 100 g/L cellulose clearly show that continuous addition of small amounts of H₂ O₂ (at a rate of 80 µM/h) during SSF enables LPMO activity and improves lactic acid production. While further process optimization is needed, the present proof-of-concept results show that modern LPMO-containing cellulase cocktails such as Cellic CTec2 can be used in SSF setups, without sacrificing the LPMO activity in these cocktails.

Visible light-exposed lignin facilitates cellulose solubilization by lytic polysaccharide monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls that limits enzyme access to the cell wall carbohydrates. Here, we show that exposing lignin to visible light facilitates cellulose solubilization by promoting formation of H2O2 that fuels LPMO catalysis. Light-driven H2O2 formation is accompanied by oxidation of ring-conjugated olefins in the lignin, while LPMO-catalyzed oxidation of phenolic hydroxyls leads to the required priming reduction of the enzyme. The discovery that light-driven abiotic reactions in Nature can fuel H2O2-dependent redox enzymes involved in deconstructing lignocellulose may offer opportunities for bioprocessing and provides an enzymatic explanation for the known effect of visible light on biomass conversion.

Enzymatic debranching is a key determinant of the xylan-degrading activity of family AA9 lytic polysaccharide monooxygenases

BACKGROUND

Previous studies have revealed that some Auxiliary Activity family 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) oxidize and degrade certain types of xylans when incubated with mixtures of xylan and cellulose. Here, we demonstrate that the xylanolytic activities of two xylan-active LPMOs, TtLPMO9E and TtLPMO9G from Thermothielavioides terrestris, strongly depend on the presence of xylan substitutions.

RESULTS

Using mixtures of phosphoric acid-swollen cellulose (PASC) and wheat arabinoxylan (WAX), we show that removal of arabinosyl substitutions with a GH62 arabinofuranosidase resulted in better adsorption of xylan to cellulose, and enabled LPMO-catalyzed cleavage of this xylan. Furthermore, experiments with mixtures of PASC and arabinoglucuronoxylan from spruce showed that debranching of xylan with the GH62 arabinofuranosidase and a GH115 glucuronidase promoted LPMO activity. Analyses of mixtures with PASC and (non-arabinosylated) beechwood glucuronoxylan showed that GH115 action promoted LPMO activity also on this xylan. Remarkably, when WAX was incubated with Avicel instead of PASC in the presence of the GH62, both xylan and cellulose degradation by the LPMO9 were impaired, showing that the formation of cellulose-xylan complexes and their susceptibility to LPMO action also depend on the properties of the cellulose. These debranching effects not only relate to modulation of the cellulose-xylan interaction, which influences the conformation and rigidity of the xylan, but likely also affect the LPMO-xylan interaction, because debranching changes the architecture of the xylan surface.

CONCLUSIONS

Our results shed new light on xylanolytic LPMO9 activity and on the functional interplay and possible synergies between the members of complex lignocellulolytic enzyme cocktails. These findings will be relevant for the development of future lignocellulolytic cocktails and biomaterials.

Continuous photometric activity assays for lytic polysaccharide monooxygenase-Critical assessment and practical considerations

Lytic polysaccharide monooxygenase (LPMO) is a monocopper-dependent enzyme that cleaves glycosidic bonds by using an oxidative mechanism. In nature, they act in concert with cellobiohydrolases to facilitate the efficient degradation of lignocellulosic biomass. After more than a decade of LPMO research, it has become evident that LPMOs are abundant in all domains of life and fulfill a diverse range of biological functions. Independent of their biological function and the preferred polysaccharide substrate, studying and characterizing LPMOs is tedious and so far mostly relied on the discontinuous analysis of the solubilized reaction products by HPLC/MS-based methods. In the absence of appropriate substrates, LPMOs can engage in two off-pathway reactions, i.e., an oxidase and a peroxidase-like activity. These futile reactions have been exploited to set up easy-to-use continuous spectroscopic assays. As the natural substrates of newly discovered LPMOs are often unknown, widely applicable, simple, reliable, and robust spectroscopic assays are required to monitor LPMO expression and to perform initial biochemical characterizations, e.g., thermal stability measurements. Here we provide detailed descriptions and practical protocols to perform continuous photometric assays using either 2,6-dimethoxyphenol (2,6-DMP) or hydrocoerulignone as colorimetric substrates as a broadly applicable assay for a range of LPMOs. In addition, a turbidimetric measurement is described as the currently only method available to continuously monitor LPMOs acting on amorphous cellulose.

Enhanced in situ H2O2 production explains synergy between an LPMO with a cellulose-binding domain and a single-domain LPMO

Lytic polysaccharide monooxygenases (LPMOs) are mono-copper enzymes that catalyze oxidative depolymerization of recalcitrant substrates such as chitin or cellulose. Recent work has shown that LPMOs catalyze fast peroxygenase reactions and that, under commonly used reaction set-ups, access to in situ generated H₂O₂ likely limits catalysis. Based on a hypothesis that the impact of a cellulose-binding module (CBM) on LPMO activity could relate to changes in in situ H₂O₂ production, we have assessed the interplay between CBM-containing ScLPMO10C and its truncated form comprising the catalytic domain only (ScLPMO10C_TR). The results show that truncation of the linker and CBM leads to elevated H₂O₂ production and decreased enzyme stability. Most interestingly, combining the two enzyme forms yields strong synergistic effects, which are due to the combination of high H₂O₂ generation by ScLPMO10C_TR and efficient productive use of H₂O₂ by the full-length enzyme. Thus, cellulose degradation becomes faster, while enzyme inactivation due to off-pathway reactions with excess H₂O₂ is reduced. These results underpin the complexity of ascorbic acid-driven LPMO reactions and reveal a potential mechanism for how LPMOs may interact synergistically during cellulose degradation.

Comparison of six lytic polysaccharide monooxygenases from Thermothielavioides terrestris shows that functional variation underlies the multiplicity of LPMO genes in filamentous fungi

Lytic polysaccharide monooxygenases (LPMOs) are mono-copper enzymes that oxidatively degrade various polysaccharides. Genes encoding LPMOs in the AA9 family are abundant in filamentous fungi while their multiplicity remains elusive. We describe a detailed functional characterization of six AA9 LPMOs from the ascomycetous fungus Thermothielavioides terrestris LPH172 (syn. Thielavia terrestris). These six LPMOs were shown to be upregulated during growth on different lignocellulosic substrates in our previous study. Here, we produced them heterologously in Pichia pastoris and tested their activity on various model and native plant cell wall substrates. All six T. terrestris AA9 (TtAA9) LPMOs produced hydrogen peroxide in the absence of polysaccharide substrate and displayed peroxidase-like activity on a model substrate, yet only five of them were active on selected cellulosic substrates. TtLPMO9A and TtLPMO9E were also active on birch acetylated glucuronoxylan, but only when the xylan was combined with phosphoric acid-swollen cellulose (PASC). Another of the six AA9s, TtLPMO9G, was active on spruce arabinoglucuronoxylan mixed with PASC. TtLPMO9A, TtLPMO9E, TtLPMO9G, and TtLPMO9T could degrade tamarind xyloglucan and, with the exception of TtLPMO9T, beechwood xylan when combined with PASC. Interestingly, none of the tested enzymes were active on wheat arabinoxylan, konjac glucomannan, acetylated spruce galactoglucomannan, or cellopentaose. Overall, these functional analyses support the hypothesis that the multiplicity of the fungal LPMO genes assessed in this study relates to the complex and recalcitrant structure of lignocellulosic biomass. Our study also highlights the importance of using native substrates in functional characterization of LPMOs, as we were able to demonstrate distinct, previously unreported xylan-degrading activities of AA9 LPMOs using such substrates.

IMPORTANCE The discovery of LPMOs in 2010 has revolutionized the industrial biotechnology field, mainly by increasing the efficiency of cellulolytic enzyme cocktails. Nonetheless, the biological purpose of the multiplicity of LPMO-encoding genes in filamentous fungi has remained an open question. Here, we address this point by showing that six AA9 LPMOs from a single fungal strain have various substrate preferences and activities on tested cellulosic and hemicellulosic substrates, including several native xylan substrates. Importantly, several of these activities could only be detected when using copolymeric substrates that likely resemble plant cell walls more than single fractionated polysaccharides do. Our results suggest that LPMOs have evolved to contribute to the degradation of different complex structures in plant cell walls where different biomass polymers are closely associated. This knowledge together with the elucidated novel xylanolytic activities could aid in further optimization of enzymatic cocktails for efficient degradation of lignocellulosic substrates and more.