Biology subjects

Eijsink, V. G. H.

Publications and source records attributed to Eijsink, V. G. H..

17 recordsLinked to original sources

bioRxiv2026

Conserved copper(I)-binding auxiliary domains link virulence-associated LPMOs to copper homeostasis in the intestinal environment

Multidomain lytic polysaccharide monooxygenases (LPMOs) are widely distributed in human pathogenic bacteria and increasingly recognized for promoting host interactions and virulence. Recent work has shown that immunizing mice with CbpD, a trimodular LPMO from Pseudomonas aeruginosa, provides protection against lethal P. aeruginosa infection. In several human intestinal pathogenic bacteria, LPMOs occur as tetra- and pentamodular proteins and their ability to interact with the host and facilitate virulence has primarily been ascribed to their ability to bind to N-acetylglucosamine containing glycans. Recently, AlphaFold predictions and substrate-binding studies of the Vibrio cholerae colonization factor GbpA suggested the presence of a copper-binding site in its non-catalytic third domain. In light of the recent demonstration that MUC2, the primary intestinal mucin, harbors two conserved and distinct copper binding sites for Cu(II) and Cu(I), we hypothesized that the auxiliary non-catalytic copper-binding domains of intestinal LPMOs evolved as a response to the intestinal environment. Here, we examine GbpA and homologous multidomain LPMOs from food-borne intestinal disease-causing Gram-positive bacteria from the genera Bacillus and Listeria. By combining mutagenesis with biochemical, spectroscopic, and computational approaches, we demonstrate that these multidomain LPMOs contain conserved, yet structurally distinct copper(I)-binding motifs on their non-catalytic third domain. A comprehensive review and reassessment of the literature spanning the past two decades reveals consistent links between the copper-binding ability of these LPMOs and host-pathogen interactions. Thus, our findings link these LPMOs to copper management in the intestine, offering an explanation for why their unique architecture is preserved across different bacterial lineages causing intestinal disease.

biochemistry↗

bioRxiv2025

Discovery and characterization of bacterial unspecific peroxygenase-like heme-thiolate enzymes

Unspecific peroxygenases (UPOs, EC. 1.11.2.1) are promising biocatalysts for the oxyfunctionalization of organic molecules and the synthesis of industrially relevant compounds due to their vast repertoire of catalyzed reactions. To date, thousands of putative UPO genes have been identified in eukaryotic genomes, most of them in the Ascomycota and Basidiomycota phyla, and several UPOs have been characterized. Remarkably, no related enzymes have ever been reported in prokaryotic organisms. Here, we describe the discovery of a novel family of diverse bacterial heme-thiolate peroxygenases through structure database mining, followed by functional characterization of selected representatives. The bacterial UPO-like proteins (BUPOs) are structurally analogous to family I ("short") fungal UPOs, despite having sequence similarity below 20%. Expression of one of these proteins (HydBUPO) in its native host (Hydrogenophaga sp. A37) was confirmed by proteomics. Several BUPOs were cloned and expressed in Escherichia coli. In biochemical assays, the BUPOs were able to catalyze one-electron oxidation (peroxidase activity) of ABTS and 2,6-dimethoxyphenol, and two-electron oxidation (peroxygenase activity) of naphthalene, indole, 3-phenyl-1-propanol and 16-hydroxypalmitic acid, using hydrogen peroxide as co-substrate. These enzymes thus represent a new family of bacterial heme-thiolate peroxygenases that share structural and functional features with eukaryotic UPOs, offering new potential candidates for developing industrially relevant biocatalysts.

biochemistry↗

bioRxiv2025

A single-domain expansin-like protein from Gloeophyllum trabeum able to cleave xylan

Expansin-related proteins (ERPs) are a broad group of plant cell wall-loosening proteins and are considered non-catalytic as, to date, no cell wall-derived products have been observed as a result of catalysis, despite the presence of a domain that resembles the catalytic domains of GH45 endoglucanases. Here, we report catalytic activity for a single-domain ERP, GtEXPN_133317, from the brown-rot fungus Gloeophyllum trabeum, which is highly expressed in the early phase of spruce colonization. We demonstrate enzyme-dependent formation of xylan-derived products, such as glucuronylated xylo-oligosaccharides, using high-performance anion exchange chromatography with pulsed amperometric detection. Structure-based multiple sequence alignment of ERPs with GH45 endoglucanases showed that, next to a single conserved aspartate (Asp87 in GtEXPN_133317) present in all ERPs and GH45s, fungal ERPs contain a second conserved acidic residue (Asp25 in GtEXPN_133317). Mutation of these two conserved amino acids, Asp87 and Asp25, led to a nearly complete loss of xylanolytic activity. While these findings do not exclude the possibility of a non-catalytic plant cell wall-loosening mechanism, they show that ERPs likely have other modes of action besides what the current paradigm states. Significance statementProtein-mediated plant cell wall-loosening is a natural process that enables plant growth and improves cell wall accessibility for microorganisms. Expansin-related proteins (ERPs) are key to this process, but their mechanism is not fully understood. Traditionally, ERPs are seen as non-catalytic, disrupting non-covalent bonds holding the cellulose network together. We have investigated an expansin-like protein from a fungal saprotroph and demonstrate its catalytic activity by showing product formation from glucuronoxylan and identifying key residues associated with this activity. This activity, although so far only shown for one protein, challenges the current paradigm that ERPs are non-catalytic, shedding new light on plant cell wall architecture and dynamics as well as on the potential roles of ERPs in plant-pathogen interactions.

biochemistry↗

bioRxiv2025

Production and evaluation of fluorophore-doped polymer substrates to screen for plastic-degrading enzymes

Fast and sensitive analytical methods are the key to efficient screening of plastic-degrading enzymes. While liquid and gas chromatography with mass spectrometry detection offer great power, the cost of the equipment is high, and the methods may not be straightforward when studying crude environmental samples. Here, we present a streamlined and affordable approach to assess the enzymatic deconstruction of insoluble synthetic polymers by blending them with a fluorescent probe, rhodamine 6G, and we evaluate this screening method using poly(ethylene terephthalate) (PET) as a model material. Our results indicate that enzymatic depolymerization of the rhodamine-doped PET can be observed in a high-throughput fashion by following release of the fluorophore. The fluorescence data obtained during the hydrolysis of rhodamine-doped PET by 14 engineered PET hydrolases, produced with a robotic platform, correlated with the quantitative chromatographic analysis of PET degradation products. Remarkably, the use of the rhodamine-loaded PET substrate resulted in negligibly low background signals even when detecting PETase activity in crude cell lysates, suggesting suitability for screening of a wide variety of samples. Encouraged by these results, we next produced a selection of polyethylene- and nylon-based materials loaded with rhodamine 6G. While rapid leaching of fluorophore observed with nylon substrates limits the utility of the method for detecting nylonase activity, the rhodamine-loaded polyethylene showed promising performance in passive diffusion tests, indicating that this latter substrate may be used to screen for polyolefin-degrading enzymes.

biochemistry↗

bioRxiv2025

Mechanistic Insights into Keratin Degradation by Onygena corvina

Keratin-rich byproducts from the poultry, textile, and leather industries pose a significant challenge for sustainable waste management due to their highly recalcitrant nature. While microbial degradation may offer a viable solution, the mechanisms underlying keratin breakdown remain largely unexplored. In this study, we employed a high-resolution proteogenomic approach to characterize the keratinolytic machinery of Onygena corvina, a non-pathogenic saprophytic fungus. Using a membrane agar plate method with insoluble substrates, we obtained secretomes enriched in secreted and substrate-bound proteins during growth on - and {beta}-keratin-rich substrates, specifically wool and feather meal. Our findings reveal that O. corvina has a richer proteolytic machinery than previously reported, including enzymes that are used across keratin types, as well as enzymes that are specifically targeted to either - or {beta}-keratin. In addition to proteases, the secretomes contain numerous other proteins, including cell wall-modifying enzymes, oxidoreductases, esterases, phosphatases, and sialidases that are involved in the deconstruction of keratin. We propose that these additional enzymes destabilize keratin through a combination of mechanical keratinolysis, removal of post-translational modifications, reduction of disulfide bonds, and cleavage of isopeptide bonds, thereby enhancing proteolytic accessibility. Interestingly, keratin degradation by O. corvina was most efficient when using mixed substrates containing both feather and wool meal. These novel insights into the keratinolytic system of O. corvina underscore the importance of considering synergistic enzyme interactions when developing biotechnological approaches for valorization of keratin-rich by-products.

molecular biology↗

bioRxiv2025

Functional characterization of multi-domain LPMOs from marine Vibrio species reveals modulation of enzyme activity by domain-domain interactions

Several bacterial pathogens secrete multi-domain enzymes known as lytic polysaccharide monooxygenases (LPMOs) that are important for virulence. One example is the Vibrio cholerae virulence factor GbpA (VcGbpA), in which an N-terminal LPMO domain is followed by two domains of unknown function called GbpA2 and GbpA3, and a C-terminal chitin-binding domain, called CBM73. In-depth functional characterization of full-length and truncated variants of VcGbpA and a homologue from V. campbellii (previously V. harveyi; VhGbpA) showed that the catalytic LPMO domains of these proteins exhibit properties similar to natural single-domain LPMOs with established roles in chitin degradation. Interestingly, binding to chitin and efficient degradation of this substrate were affected by the presence of the GbpA2 and GbpA3 domains. Combined with structural predictions and analyses of sequence conservation, our data suggests that GbpA3 has evolved to interact with the reduced copper site to prevent off-pathway reactions in the absence of substrate. Substrate binding by CBM73 weakens this interaction, enabling the activation of the LPMO only when substrate is present. These observations shed new light into the functionality of these multi-domain LPMOs and uncover a novel mechanism for regulating LPMO activity.

biochemistry↗

bioRxiv2025

Improved Genome Assembly of Onygena corvina, a Keratin-Degrading Fungus

ObjectiveOnygena corvina is a non-pathogenic, saprophytic fungus that colonizes feathers, hooves, and hair, and represents a valuable source of keratin-degrading enzymes. Previously, the genome of O. corvina has been assembled based on Illumina short-read sequencing, yielding a reference genome composed of 521 contigs with a contig N50 of 0.229 Mb. ResultsHere, we report an improved O. corvina genome assembly generated using a high-quality hybrid approach that combines Illumina short-read and Oxford Nanopore long-read sequencing. The new assembly consists of only 13 contigs totaling 21.8 Mb, with an N50 of 4.4 Mb, and has a completeness of 98.97%. A total of 7,232 protein-coding genes were identified using an integrative approach that combines de novo predictions, homology-based inferences, and RNA-sequencing-guided evidence. Notably, 158 putative protease-coding genes were identified representing a substantial increase from the 73 predicted proteases in the previous annotation. Our improved genome assembly and associated gene annotations will facilitate comparative genomics, and high-resolution mapping of transcriptomic and proteomic data, to advance research on fungal physiology and fungal abilities to degrade recalcitrant substrates such as keratin.

microbiology↗

bioRxiv2025

Redox robustness drives LPMO evolution

Enzymes known as lytic polysaccharide monooxygenases (LPMOs) are exceptionally powerful small redox enzymes that master the controlled generation and productive use of potentially damaging hydroxyl radicals in what is essentially a H2O2-driven peroxygenase reaction. We have used ancestral sequence reconstruction and enzyme resurrection to unravel evolutionary steps leading to this unprecedented catalytic power. Real-time monitoring of copper re-oxidation and amino acid radical formation showed evolutionary improvement of both the capacity to avoid futile turnover of H2O2 and the ability to scavenge damaging radicals resulting from such turnover through a hole hopping pathway. These results show how selective pressure imposed by the need for generating a highly oxidizing intermediate shapes metalloenzymes, involving large parts of the enzyme, well beyond the catalytic center.

evolutionary biology↗

bioRxiv2025

Discovery and characterization of a copper-binding carbohydrate-binding module (CBM) regulating the activity of lytic polysaccharide monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that hydroxylate recalcitrant polysaccharides such as cellulose. Like other redox enzymes, LPMOs face challenges in handling the reactive oxygen species generated at their active site, which must be controlled to prevent off-pathway reactions that lead to enzyme inactivation. In the case of LPMOs, oxidative damage may be self-reinforcing because free copper released from damaged catalytic centers will promote abiotic redox reactions that generate reactive oxygen species. Here we show that some members of a widely spread family of carbohydrate-binding modules (CBM2s) have evolved the ability to bind copper and that this ability is exclusively found in CBM2s that are appended to LPMOs. We show that the copper site in these CBM2s protects the LPMO from inactivation both by scavenging free copper, preferably Cu(I), and by interacting directly with the reduced catalytic copper site of the LPMO, thus preventing the enzyme from engaging in off-pathway reactions. These effects are demonstrated by studies on the redox stability of a series of engineered LPMO variants as well as AlphaFold3 models of the CBM2-containing enzymes. Interestingly, the copper site and the cellulose-binding surface are located on different sides of these CBM2s, enabling a mode of action in which the CBM inhibits potentially damaging LPMO activity in the absence of substrate, while such inhibition would be relieved upon binding of the CBM2 to cellulose. These findings show that CBMs have biologically relevant functions beyond carbohydrate-binding and reveal a mechanism for substrate-dependent regulation of LPMO reactivity.

biochemistry↗

bioRxiv2024

Revisiting the activity of two poly(vinyl chloride)- and polyethylene-degrading enzymes

Biocatalytic degradation of non-hydrolyzable plastics is a rapidly growing field of research, driven by the global accumulation of waste. Enzymes capable of cleaving the carbon-carbon bonds in synthetic polymers are highly sought-after as they may provide tools for environmentally friendly plastic recycling. Despite some reports of oxidative enzymes acting on non-hydrolyzable plastics, including polyethylene or poly(vinyl chloride), the notion that these materials are susceptible to efficient enzymatic degradation remains controversial, partly driven by a general lack of studies independently reproducing previous observations. We attempted to replicate two recent studies reporting that deconstruction of polyethylene and poly(vinyl chloride) can be achieved using an insect hexamerin from Galleria mellonella (so-called "Ceres") or a bacterial catalase-peroxidase from Klebsiella sp., respectively. Reproducing previously described experiments with the recombinant proteins, we did not observe any activity on plastics using multiple reaction conditions and multiple substrate types. Digging deeper into the discrepancies between the previous data and our observations, we show how and why the original experimental results may have been misinterpreted, leading to the erroneous claim that enzymatic deconstruction of polyethylene and poly(vinyl chloride) had occurred. Our results should lead to caution when interpreting the growing amount of literature claiming enzymatic degradation of non-hydrolyzable plastics.

biochemistry↗

bioRxiv2023

Experimental and computational insights into the functional and structural role of the linker region of a two-domain lytic polysaccharide monooxygenase

A considerable number of lytic polysaccharide monooxygenases (LPMOs) and other carbohydrate-active enzymes are modular, with catalytic domains being tethered to additional domains, such as carbohydrate-binding modules, by flexible linkers. While such linkers may affect the structure, function, and stability of the enzyme, their roles remain largely enigmatic, as do the reasons for natural variation in length and sequence. Here, we have explored linker functionality using the two-domain cellulose-active ScLPMO10C from Streptomyces coelicolor as a model system. In addition to investigating the wild-type enzyme, we engineered three linker variants to address the impact of both length and sequence and characterized these using SAXS, NMR, MD simulations, and functional assays. The resulting data revealed that, in the case of ScLPMO10C, linker length is the main determinant of linker conformation and enzyme performance. Both the wild-type and a serine-rich variant, which have the same linker length, demonstrated better performance compared to those with either a shorter or longer linker. A highlight of our findings was the substantial thermostability observed in the serine-rich variant. Importantly, the linker affects thermal unfolding behavior and enzyme stability. In particular, unfolding studies show that the two domains unfold independently when mixed, while the full-length enzyme shows one cooperative unfolding transition, meaning that the impact of linkers in biomass processing enzymes is more complex than mere structural tethering.

biochemistry↗

bioRxiv2023

Following the fate of lytic polysaccharide monooxygenases (LPMOs) under oxidative conditions by NMR spectroscopy

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyze oxidative cleavage of polysaccharides, such as cellulose and chitin. LPMO action is key to the efficient varlorization of biomass, but the instability of LPMOs in turnover conditions limits their efficiency. LPMO catalysis requires the presence of a reductant, such as ascorbic acid, and hydrogen peroxide, which can be generated in situ in the presence of molecular oxygen and various electron donors.. While it is known that reduced LPMOs are prone to auto-catalytic oxidative damage due to off-pathway reactions with the oxygen co-substrate, little is known about the structural consequences of such damage. Here, we present atomic-level insight into how the structure of the chitin-active SmLPMO10A is affected by oxidative damage, using NMR and CD spectroscopy. Incubation with ascorbic acid, led to rearrangements of aromatic residues, followed by more profound structural changes near the copper active site and loss of activity. Longer incubation times induced changes in larger parts of the structure, indicative of progressing oxidative damage. Incubation with ascorbic acid in the presence of chitin led to similar changes in the observable (i.e., not substrate-bound) fraction of the enzyme. Upon subsequent addition of H2O2, which drastically speeds up chitin hydrolysis, NMR signals corresponding to seemingly intact SmLPMO10A reappeared, indicating dissociation of catalytically competent LPMO. Activity assays confirmed that SmLPMO10A retained catalytic activity when pre-incubated with chitin before being subjected to conditions that induce oxidative damage. Overall, this study provides structural insights into the process of oxidative damage of SmLPMO10A and demonstrates the protective effect of the substrate. The impact of turnover conditions on aromatic residues in the core of the enzyme suggests a role for these residues in dealing with redox-active species generated in the copper center.

biochemistry↗

bioRxiv2021

NMR structures and functional roles of two related chitin-binding domains of a lytic polysaccharide monooxygenase from Cellvibrio japonicus

Among the extensive repertoire of carbohydrate-active enzymes, lytic polysaccharide monooxygenases (LPMOs) have a key role in recalcitrant biomass degradation. LPMOs are copper-dependent enzymes that catalyze oxidative cleavage of glycosidic bonds in polysaccharides such as cellulose and chitin. Several LPMOs contain carbohydrate-binding modules (CBMs) that are known to promote LPMO efficiency. Still, structural and functional properties of some of these CBMs remain unknown and it is not clear why some LPMOs, like CjLPMO10A from Cellvibrio japonicus, have two CBMs (CjCBM5 and CjCBM73). Here, we studied substrate binding by these two CBMs to shine light on the functional variation, and determined the solution structures of both by NMR, which includes the first structure of a member of the CBM73 family. Chitin-binding experiments and molecular dynamics simulations showed that, while both CBMs bind crystalline chitin with Kd values in the {micro}M range, CjCBM73 has higher affinity than CjCBM5. Furthermore, NMR titration experiments showed that CjCBM5 binds soluble chitohexaose, whereas no binding to soluble chitin was detected for CjCBM73. These functional differences correlated with distinctly different architectures of the substrate-binding surfaces of the two CBMs. Taken together, these results provide insight into natural variation among related chitin-binding CBMs and the possible functional implications of such variation.

biochemistry↗

bioRxiv2020

Bacteria in biogas digestates for reduced climate forcing

Inoculating agricultural soils with N2O-respiring bacteria (NRB) can reduce N2O-emissions, but would be impractical as a standalone operation. Here we demonstrate that digestates obtained after biogas production are suitable substrates and vectors for NRB. We show that indigenous NRB in digestates grew to high abundance during anaerobic enrichment under N2O. Gas-kinetics and meta-omic analyses showed that these NRB's, recovered as metagenome-assembled genomes (MAGs), grew by harvesting fermentation intermediates of the methanogenic consortium. Three NRB's were isolated, one of which matched the recovered MAG of a Dechloromonas, deemed by proteomics to be the dominant producer of N2O-reductase in the enrichment. While the isolates harbored genes required for a full denitrification pathway and could thus both produce and sequester N2O, their regulatory traits predicted that they act as N2O sinks in soil, which was confirmed experimentally. The isolates were grown by aerobic respiration in digestates, and fertilization with these NRB-enriched digestates reduced N2O emissions from soil. Our use of digestates for low-cost and large-scale inoculation with NRB in soil can be taken as a blueprint for future applications of this powerful instrument to engineer the soil microbiome, be it for enhancing plant growth, bioremediation, or any other desirable function.

microbiology↗

bioRxiv2020

Synthesis of Glycoconjugates Utilizing the Regioselectivity of a Lytic Polysaccharide Monooxygenase

Polysaccharides from plant biomass are the most abundant renewable chemicals on Earth and can potentially be converted to a wide variety of useful glycoconjugates. While anomeric hydroxyl groups of carbohydrates are amenable to a variety of useful chemical modifications, selective cross-coupling to non-reducing ends has remained challenging. Several lytic polysaccharide monooxygenases (LPMOs), powerful enzymes known for their application in cellulose degradation, specifically oxidize non-reducing ends, introducing carbonyl groups that can be utilized for chemical coupling. This study provides a simple and highly specific approach to produce oxime-based glycoconjugates from LPMO-functionalized oligosaccharides. The products are evaluated by HPLC, mass spectrometry and NMR. Furthermore, we demonstrate potential biodegradability of these glycoconjugates using selective enzymes.

biochemistry↗

bioRxiv2019

Molecular mechanism of the chitinolytic monocopper peroxygenase reaction

Lytic polysaccharide monooxygenases (LPMOs) are a recently discovered class of monocopper enzymes, broadly distributed across the Tree of Life. We recently reported that LPMOs can use H2O2 as an oxidant, revealing a novel reaction pathway. Here, we aimed to elucidate the H2O2-mediated reaction mechanism with experimental and computational approaches. In silico studies suggest that a network of hydrogen bonds, involving both the enzyme and the substrate, brings H2O2 into a strained reactive conformation, and guides the derived hydroxyl radical towards formation of a copper-oxyl intermediate. The initial H2O2 homolytic cleavage and subsequent hydrogen atom abstraction from chitin by the copper-oxyl intermediate are suggested to be the main energy barriers. Under single turnover conditions, stopped-flow fluorimetry demonstrates that LPMO-Cu(II) reduction to Cu(I) is a fast process compared to the re-oxidation reactions. We found that re-oxidation of LPMO-Cu(I) is 2000-fold faster with H2O2 than with O2, the latter being several orders of magnitude slower than rates reported for other monooxygenases. In agreement with the notion of ternary complex formation, when chitin is added, re-oxidation by H2O2 is accelerated whereas that by O2 slows. Simulations indicated that Glu60, a highly-conserved residue, gates the access to the confined active site and constrains H2O2 during catalysis, and Glu60 mutations significantly decreased the enzyme performance. By providing molecular and kinetic insights into the peroxygenase activity of chitinolytic LPMOs, this study will aid the development of applications of enzymatic and synthetic copper catalysis and contribute to understanding pathogenesis, notably chitinolytic plant defenses against fungi and insects. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/541292v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@92826org.highwire.dtl.DTLVardef@12b0a19org.highwire.dtl.DTLVardef@a3fa2aorg.highwire.dtl.DTLVardef@17cfa80_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2018

From proteins to polysaccharides: lifestyle and genetic evolution of Coprothermobacter proteolyticus.

Microbial communities that degrade lignocellulosic biomass are typified by high levels of species- and strain-level complexity as well as synergistic interactions between both cellulolytic and non-cellulolytic microorganisms. Coprothermobacter proteolyticus frequently dominates thermophilic, lignocellulose-degrading communities with wide geographical distribution, which is in contrast to reports that it ferments proteinaceous substrates and is incapable of polysaccharide hydrolysis. Here we deconvolute a highly efficient cellulose-degrading consortium (SEM1b) that is co-dominated by Clostridium (Ruminiclostridium) thermocellum- and multiple heterogenic strains affiliated to C. proteolyticus. Metagenomic analysis of SEM1b recovered metagenome-assembled genomes (MAGs) for each constituent population, whilst in parallel two novel strains of C. proteolyticus were successfully isolated and sequenced. Annotation of all C. proteolyticus genotypes (two strains and one MAG) revealed their genetic acquisition of various carbohydrate-active enzymes (CAZymes), presumably derived from horizontal gene transfer (HGT) events involving C. thermocellum- or Thermotogae-affiliated populations that are historically co-located. HGT material included whole saccharolytic operons and dockerin-encoding enzymatic subunits that are synonymous with cellulosomes. Finally, temporal genome-resolved metatranscriptomic analysis of SEM1b revealed expression of C. proteolyticus CAZymes at different SEM1b life-stages as well as co-expression of CAZymes from multiple SEM1b populations, inferring deeper microbial interactions that are dedicated towards co-degradation of cellulose and hemicellulose. We show that C. proteolyticus, a ubiquitous keystone population, consists of closely related strains that have adapted via HGT to degrade both oligo- and longer polysaccharides present in decaying plants and microbial cell walls, thus explaining its dominance in thermophilic anaerobic digesters on a global scale.

microbiology↗